Wrapping a whirlwind day of campaigning, President Barack Obama joined Bill Clinton — the last Democratic president, and vocal advocate for Obama — at a massive rally Saturday evening in northern Virginia. 

Before a crowd estimated at 24,000, Obama both literally and figuratively embraced Clinton, who has emerged as one of the most dogged advocates for the president's re-election campaign this fall. 

"He has been traveling all across the country for this campaign. He's been laying out the stakes so well that our team basically calls him the 'Secretary of Explaining Stuff,'" Obama said. "He was a great president; he has been a great friend."

As the final weekend of the 2012 campaign raised the question of which candidate, Obama or Republican presidential nominee Mitt Romney, would best move Washington past its intractable problems, Clinton, a president who has only grown more popular since leaving office, offered Obama his imprimatur. 

"As you see, I have given my voice in the service of my president," the hoarse former president said, following some local favorites, the Dave Matthews Band, at the rally in suburban Washington. 

NBC Politics coverage of the 2012 campaign:

• Uncertain finale looms amid weekend campaign blitz
• Romney implores Colorado for 'one last push'
• Biden zings Romney in Colorado
• Ryan travels to Pennsylvania, trying to put state in play
• Obama plays up 'trust' in battleground Ohio
• Obama aide explains 'voting is best revenge' comment
• Ryan: 'We believe in change and hope'
• Romney strikes optimistic tone as final weekend opens
• Polls: Obama stays ahead in Ohio, deadlocked with Romney in Fla.
• GOP's chances at Senate imperiled by self-inflicted wounds

Both Obama and Romney spent the day criss-crossing the United States to make a firmly centrist appeal, each of them trying to sound upbeat as the clock counts down on Election 2012. Each candidate drew thousands — sometimes tens of thousands — of supporters to rallies in Iowa, Wisconsin, Colorado, Iowa, Virginia, Ohio and beyond. And each candidate argued he was the one who could break through the gridlock in a Congress beset for the past two years by bitter partisan fights.

"You know that if the president is re-elected, he'll still be unable to work with the people in Congress," Romney told a sprawling crowd in Colorado. "He's ignored them. He's blamed them. He's attacked them."

Romney spent much of the campaign's final weekend arguing he was the candidate of "change," co-opting Obama's 2008 message to use four years later against the president. 

Whether the Republican candidate's claim to to the mantle of change would resonate with a handful of remaining swing voters in just a few battleground states was unclear. Obama seemed to enjoy an edge in states like Iowa, leading Romney by five points among likely voters, according to the Des Moines Register's final poll. But a WMUR poll of New Hampshire also found the president and Romney tied, at 47 percent. 

That neither Obama or Romney had managed to open a solid advantage over the other in the final hours of the campaign only raised the stakes for the final series of events on Sunday and Monday. Both Obama and Romney — along with Vice President Biden and Republican vice presidential nominee Paul Ryan — were set to hit the road on Sunday. Obama was set to travel to Colorado, Florida, Ohio and Colorado; Romney's schedule would take him to Iowa, Ohio and Pennsylvania.

ENGLEWOOD, CO — Republican presidential nominee Mitt Romney implored Colorado voters for "one final push" in his final rally Saturday, making his entreaty to the largest and most boisterous crowd of the day.

"One final push is gonna get us there. We’ve had a lot of short nights and long days and now we’re close," Romney told a crowd of more than 17,000 supporters gathered at an outdoor amphitheater. "The door to a brighter future is there – it’s open, waiting for us.  I need your vote, I need your work, I need your help."

Colorado voters have turned out in large numbers for Romney at recent rallies here, and he'll need the kind of high energy he received tonight to move this state, which most polls show knotted up, back into the Republican column on Tuesday.

In his fourth and final campaign stop of the day, Romney continued to appeal primarily to independent voters with his "closing argument" stump speech, telling his assembled crowd that the president had failed to live up to his lofty promises of change, and would continue to fail to work with Republicans in Congress should be he granted a second term. 

"Change can't be measured in speeches; it is measured in achievements. And four years ago, candidate Obama promised to do so very much. But he has fallen so very short," Romney said. "He promised he would be a post-partisan president, but he has been most partisan — dividing, attacking, blaming."

Romney also added a local touch to his final Colorado appearance. Retelling the tale of a Boy Scout group's flag — thought lost in the Challenger space shuttle explosion, but later recovered unharmed and returned to them — Romney invited a special guest out onstage: Maj. William Tolbert, the US Air Force officer and scoutmaster from Monument, Colorado who figures so prominently in the story, carrying the flag itself, encased in glass.

"That," said Romney as Tolbert stood beside him and the crowd cheered its approval, "is a great flag, representing the greatest nation in the history of the Earth."

COLORADO SPRINGS, CO — Mitt Romney offered Colorado voters a final look at his presidential résumé on Saturday afternoon, delivering an updated version of his "closing argument" speech to some 4,500 supporters gathered in an airplane hangar here.

"We've got to change course because unless we do we may be looking at another recession," Romney warned. "The question of this election comes down to this: Do you want more of the same or do you want real change?"

Romney will make his "real change" pitch once more for Colorado voters this evening, in his final rally in a state expected to have razor thin margins as votes are tallied on Election Day. As he did in Wisconsin on Friday, Romney focused his remarks on promises to work across the aisle, on keeping an economic focus if elected, and on his resume as a change agent in business and in government.

“You know when I’m elected the economy and American jobs will still be stagnant, but I’m not going to waste any time complaining my predecessor," Romney said. "I will not spend my effort and time trying to pass partisan legislation that’s unrelated to the economy and jobs. From day one, I’m going to go to work to help Americans get back to work.”

Romney was joined on the stump today by his wife Ann, who along with a coterie of top aides usually based in Boston, is traveling with Romney for the final three day stretch of the campaign. Taking the stage here before a large an energetic crowd, she was visibly emotional as she recalled the long road traveled thus far in the campaign.

"That is amazing, to walk in and have this kind of emotion come to us.  It makes me believe we can win Colorado," Mrs. Romney said. "It has been quite a journey. It’s coming to a close. We have three more days."

PUEBLO, Colo. -- It's rare that an audience asks the famously audible Joe Biden to speak up.

But with the acoustics in Pueblo's Central High School gymnasium leaving many of the thousand attendees at his Saturday afternoon rally unable to hear him, they did.

"I wish to hell they'd turn this mic up!" an annoyed Biden declared loudly upon hearing their pleas for more volume.

Biden, who is known to read media coverage of his slip-ups and frequently notes in front of audiences that he "got in trouble" with the press for mistakes,  joked about the kind of headlines that the sound situation could garner as he belted out the remainder of his remarks.

"I'm going to hear a press report," he said as the audience giggled at his imagined headline. "'Biden screamed at the audience.'"

MIDDLETOWN, Penn. — Republican vice presidential nominee Paul Ryan spearheaded a last-minute effort by Republicans to put Pennsylvania in play on Tuesday with a trip to the Keystone State on Saturday. 

As Election Day draws near, Republican presidential contender Mitt Romney's campaign has tried to expand its path to 270 electoral votes by campaigning and spending money in Pennsylvania, a state which last went for a GOP candidate in a presidential election in 1988.

“If we win Pennsylvania, we save America in three days,” Ryan told a group of supporters standing outside his rally at the Harrisburg International Airport.

President Barack Obama carried Pennsylvania during the 2008 election by more than 10 points, but in recent days, nearly $10 million in ad buys by the Romney campaign, the Republican National Committee and GOP super PACs have infiltrated the state.

“Can I just tell you how red Pennsylvania’s gonna be on Tuesday? Because I know how red it’s gonna, it’s gonna be this red, okay,” Sen. Pat Toomey, Ryan’s former roommate on Capitol Hill, said pointing to his bright red jacket.

Related: Polls: Obama stays ahead in Ohio, deadlocked with Romney in Fla.

Republican Gov. Tom Corbett also joined Ryan Saturday, just three days before the election and believes his state could determine a very tight race between Obama and Romney on Tuesday.

“The one thing I know about Pennsylvania, and I hope you remember: We are the Keystone State. Right? No offense to my friend in Virginia, or to the rest of the country. But we are the Keystone State to this nation and we are the Keystone State to this election,” Corbett said.

Slideshow: On the campaign trail

The GOP VP nominee has held three other campaign events in Pennsylvania over the last three months, but holding a rally in the state on the last weekend before the election is typically reserved for key battleground states — further indicating the GOPs desire to win the state.

“I say in 3 days, we win, Obama loses, how does that sound?” Ryan said to a very enthusiastic 2,000-person crowd before heading to the battleground states of Virginia and Florida to wrap up the last Saturday of the campaign.

ARVADA, Colo. -- Ka-zing.

Three days before the election, Vice President Joe Biden pegged his newest critique of Republican presidential nominee Mitt Romney to the semi-annual inconvenience of adjusting clocks for Daylight Savings Time, which occurs tonight.

"It’s Mitt Romney’s favorite time of the year -- because he gets to turn the clock back!" Biden told a crowd of hundreds at a suburban Denver high school.

In his remarks, the vice president accused Romney of embracing social policies out of an earlier era, pointedly noting the GOP nominee's voiced enthusiasm for "getting rid of" Planned Parenthood. 

"With all the issues facing the country, Gov. Romney has focused on for the last three months [that] he's going to get rid of Planned Parenthood" Biden said. "And by the way, he doesn't even know he doesn't control Planned Parenthood."

"He should talk to Big Bird!" he added, referencing the scuffle over public broadcasting funding that broke out during one of the presidential debates.

(In context, Romney said last spring he was going to "get rid" of federal funding for Planned Parenthood, not get rid of the entity itself.)

Biden has two events scheduled in swing state Colorado Saturday. He will campaign Sunday in Ohio.

MENTOR, OH – Driving home his final campaign message, President Barack Obama painted himself as the trustworthy choice in the campaign versus his Republican opponent, Mitt Romney.

“When you elect a president, you don’t know what kinds of emergencies may happen. You don’t know what problems he or she may deal with. But you want to be able to trust your president,” he said to a crowd of about 4,000 at a high school in this Cleveland suburb.

The president’s advisers often talk about this election as coming down to “trust,” as does the candidate himself, but his language at Saturday’s rally was particularly explicit in terms of identifying himself as the most trustworthy candidate.

Slideshow: On the campaign trail

The president was sure to toast the successes of the Mentor High School band and football team, a tribute to the homespun politics that could make the difference in battleground Ohio.

Recommended: Ryan travels to Pennsylvania, trying to put state in play

“I also understand that this band just won the state championship? Best band in Ohio right here! In the house!” he exclaimed, referring to the Fighting Cardinals Marching Band, which entertained supporters (and reporters) with elaborate arrangements of Lady Gaga and AC/DC tunes before the event started.

“And the football team is in is first playoff game tonight! So the Cardinals got a lot going on right now,” Obama continued.

Related: Polls: Obama stays ahead in Ohio, deadlocked with Romney in Fla.

Romney spokesman Ryan Williams responded to Obama comments with a reference to the president's "voting is the best revenge" comment yesterday.

“With no record to run on and no vision for the future, President Obama is resorting to false, discredited attacks and a cynical closing message urging voters to choose ‘revenge.’ Mitt Romney wants to bring people together and he wants Americans to vote for love of country. He will deliver real change for a real recovery, creating 12 million new jobs with rising take-home pay and a better future for all Americans.”

Updated at 5:50pmET: A rapidly-approaching conclusion loomed over the 2012 election on Saturday, as President Barack Obama, Republican nominee Mitt Romney, their running mates and surrogates swarmed a series of battleground states to make their closing messages.

Obama and Romney each employed a mixture of uplifting, forward-looking rhetoric with attacks on the other during a whirlwind tour of battleground states set to decide the election on Tuesday.

 Slideshow: On the campaign trail

Looking for a catalyzing moment to push past Obama in those swing states, Romney opted to play up the president's comments Friday at a rally, at which he urged supporters to vote as a means of seeking "revenge" against Republicans.

"Yesterday the president said something you may have heard by now that I think surprised a lot of people. Speaking to an audience, he said you know voting is the best 'revenge,'" Romney said. "He told his supporters, voting for revenge. Vote for revenge? Let me tell you what I’d like to tell you: Vote for love of country."

The Obama campaign, in response Saturday afternoon, called the line of attack "very small."

"I think it's interesting that that's the closing argument that the Romney campaign is making," said Obama spokesman Ben LaBolt.

Related: Obama aide explains 'voting is best revenge' comment

The remarks were consistent with Romney's effort to project momentum heading into the campaign's final weekend, riding high after drawing the largest crowd of its campaign at a Friday night rally in Ohio. The Republican ticket has essentially tried to co-opt the themes of "change" from Obama's 2008 campaign as its closing argument now against the president.

But the Romney campaign's outward optimism clashed with new polls giving Obama an ever-so-slight edge in pivotal swing states. New NBC News/Wall Street Journal/Marist polls showed Romney trailing Obama by six points among likely voters in Ohio, and by two points in Florida.

 Related: Polls: Obama stays ahead in Ohio, deadlocked with Romney in Fla.

Republican vice presidential nominee Paul Ryan's trip Saturday afternoon to Pennsylvania, a state which the GOP has only contended in the final days of the campaign, was emblematic of the campaigns' dueling perspectives toward the campaign. The Romney campaign argued it was a sign of surging momentum while the Obama campaign cast the trip as an act of desperation — a Hail Mary effort driven by foreclosed opportunities in other battleground states. (Romney will stop in Pennsylvania on Sunday.)

While the outcome on Election Day is far from assured, a certain wistfulness set in as Obama looked back at his four years in office. He argued his experience as president showed he was someone whom voters could trust, meaning to imply as well that Romney wasn't.

"When you elect a president, you don’t know what kinds of emergencies may happen. You don’t know what problems he or she may deal with," he said. "But you want to be able to trust your president."

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In this composite photo: President Barack Obama points while speaking at a campaign event at Mentor High School in Ohio, and Republican presidential nominee Mitt Romney speaks at a campaign rally in Dubuque, Iowa November 3, 2012.  

And amid the late-breaking attack by Romney meant to cast Obama as embittered, the president told a crowd in Mentor, Ohio: "I don't feel cynical. I feel hopeful."

There were signs that awareness of the campaign's approaching horizon had set in among the Romney campaign as well.

"It was very emotional when I gave my last address by myself, because I hear the voices and the passion of the people out there that are really hurting, and they are etched in my mind and my heart, as they are with Mitt," Ann Romney told the press corps traveling with her husband. "It's been an extraordinary experience."

 Recommended: Ryan travels to Pennsylvania, trying to put state in play

The full range of reflection would have to wait, though, until Wednesday. Obama and Romney — along with their running mates, Vice President Joe Biden and Ryan — each have a long list of stops ahead of them during the remainder of Saturday, Sunday and Monday. Their efforts are met by hoards of Democratic and Republican surrogates, who fanned out across the country as part of a frenzied effort in hopes of  adding a few more swing states to their candidate's column on Tuesday. 

MENTOR, OH - A day after President Obama’s “voting is the best revenge” comment became the latest object of GOP nominee Mitt Romney’s ire, Obama campaign press secretary Jen Psaki sought to explain the context of the remark.

“The message he was sending,” she said, answering a question about it while traveling to Mentor, Ohio, with reporters on Air Force One, “is if you don’t like the policies, if you don’t like the plan that Gov. Romney is putting forward, if you think that’s a bad deal for the middle class, then you can go to the voting booth and cast your ballot. It’s nothing more complicated than that.”

Obama’s offhand comment came Friday during a campaign rally in Springfield, Ohio, as supporters booed the mention of Romney’s name.

“Don't boo. Vote,” Obama said first, using a line that has become standard for him on the stump. “Voting's the best revenge,” he continued.

Earlier Saturday, Romney condemned the comment as overly negative, telling a crowd in Newington, N.H., that he thought it “surprised a lot of people.”

“Vote for revenge? Let me tell you what I’d like to tell you: Vote for love of country,” Romney said to cheers.

MARIETTA, Ohio — Republican vice presidential nominee Paul Ryan echoed Mitt Romney’s call to vote for “love of country” not out of “revenge,” seizing upon a line of President Barack Obama's

“Mitt Romney and I are asking you to vote out of love of country,” Ryan told a crowd at Marietta College. “That's what we do in this country. We don't believe in revenge. We believe in change and hope.”

Ryan was referencing remarks President Obama made Friday, also in the battleground state of Ohio, that voting against the GOP nominee is “the best revenge.”

Slideshow: On the campaign trail

Romney’s running mate added Saturday morning, in the heart of coal country: “Look, in 2008 President Obama made all these lofty promises, it sounded so good. He said that we would have bi-partisanship, that he’d bridge the gap. He said he’d cut the deficit in half, that he’d get people working again, and he’d create jobs. You see all those jobs here in Marietta? Look, it sounded good and when he got elected people naturally expected him to deliver those results but it didn’t happen and look what we got.”

The Obama re-election campaign, in an email statement, claimed the GOP ticket is “willing to say anything to win, but their rhetoric just doesn’t match reality.”

With just three days to go before Election Day, it’s the final push for both campaigns and the state of Ohio is center stage.

Recommended: Ryan travels to Pennsylvania, trying to put state in play

According to the new NBC News/Wall Street Journal/Marist poll released early Saturday morning, Obama holds a six-point advantage over Romney among likely voters, 51 percent to 45 percent, in the Buckeye State.

Related: Polls: Obama stays ahead in Ohio, deadlocked with Romney in Fla.

Romney and Ryan held their final campaign rally together before the Nov. 6 election in Ohio Friday night. They will both make several more appearances separately to the state over the next 72 hours in hopes of securing Ohio’s 18 electoral votes.

NEWINGTON, NH — Republican presidential hopeful Mitt Romney struck an upbeat note as he opened the final weekend of his campaign in the state where he launched his campaign more than 16 months ago.

"I've got a clear and unequivocal message for you: America is about to come roaring back," Romney told a chilly crowd of more than 1,000 supporters gathered to see him off for a busy Saturday of campaigning.

Romney also thanked the Granite State for its support in the Republican primary, and said they would be key to his presidential aspirations on Tuesday. The latest NBC/WSJ/Marist poll, released this week, shows Romney locked in a statistical dead heat here against President Barack Obama; the president leads 49 to 47 percent among likely voters, within the poll's margin of error.

"New Hampshire got me the Republican nomination and New Hampshire is going to get me the White House," Romney said to cheers.

From here, Romney campaigns across Iowa and Colorado on Saturday, with a packed Sunday schedule to follow that also takes him to four battleground states. Romney will next return to New Hampshire on Monday, but left behind today a team of top surrogates to barnstorm the state in his absence: Louisiana Gov. Bobby Jindal, South Dakota Sen. John Thune, who joined New Hampshire Sen. Kelly Ayotte in introducing Romney here this morning.

Romney shortened his typical stump speech this morning, but left room for a critique of Obama, telling his audience here that "talk is cheap," and that the president "wants to convince you to settle."

"Americans don’t settle – we dream, we aspire, we reach for greater things," Romney said. "And we will achieve greater things with new leadership. "

Jason Reed / REUTERS

President Barack Obama gives a thumbs up as he participates in a campaign rally in Lima, Ohio, Nov. 2, 2012.

Three days until Election Day, President Barack Obama maintains his lead in the key battleground state of Ohio and is locked in a close contest with Republican presidential nominee Mitt Romney in Florida, according to new NBC News/Wall Street Journal/Marist polls.

In Ohio, Obama holds a six-point advantage over Romney among likely voters, 51 percent to 45 percent, which is unchanged from last month’s poll in the Buckeye State.

Read the Ohio poll here

And in Florida, the president gets support from 49 percent of likely voters, while his GOP challenger gets 47 percent. Those numbers are virtually identical to the ones from October, when it was Obama 48 percent, Romney 47 percent.

Both states are two of the biggest prizes in Tuesday’s presidential contest. An Obama victory in Ohio, which awards 18 electoral votes, would put him tantalizingly close to getting to the 270 electoral votes needed to win a second term.

But an Obama loss in the Buckeye State – and a Romney win – would place a hole in the president’s Midwest firewall.

Meanwhile, Florida, which awards 29 electoral votes, is a must-win state for Romney. A Republican loss there would push Obama past 270 electoral votes – even if the president lost every other battleground state in NBC’s current map.

Obama ahead with early voters
As with the recent NBC/WSJ/Marist polls of Iowa and Wisconsin, Obama is benefitting from early voters in Ohio and Florida.

Read the Florida poll here

In the Sunshine State, 63 percent say they have already voted or plan to do so before Election Day, and Obama is winning them, 53 percent to 46 percent. But Romney is ahead among Election Day voters in Florida, 52 percent to 40 percent.

In Ohio, 35 percent say they have already voted or plan to do so, and Obama is leading them, 62 percent to 36 percent. Yet Romney is up among Election Day voters in the Buckeye State, 52 percent to 42 percent.

Strong approval for the president’s handling of Sandy
The polls were conducted after Hurricane Sandy slammed into the East Coast, and seven in 10 likely voters in Florida and Ohio approve of the president’s job in handling the hurricane and its aftermath.

“The response was overwhelmingly positive, and that was occurring across party lines,” says Lee Miringoff, director of the Marist College Institute for Public Opinion.

On handling the economy
Meanwhile, Romney has a slight advantage over Obama in Florida when it comes to which candidate would better handle the economy – 48 percent pick Romney and 46 percent back Obama.

But those numbers are reversed in Ohio, where 48 percent believe Obama would better handle the economy and 46 percent side with Romney.

On party ID
In these surveys, Democrats enjoy a nine-point party-identification advantage in Ohio and a two-point edge in Florida. Republicans have argued that a nine-point advantage is too large in this current political environment; it was eight points in the Buckeye State during Obama’s decisive 2008 victory.

If you cut that party ID advantage in half, Obama’s six-point lead in Ohio is reduced to three points.

Other numbers in the poll
Obama’s job-approval rating among likely voters stands at 48 percent in Florida and 50 percent in Ohio.

Slideshow: On the campaign trail

Reuters, Getty Images

In the final push in the 2012 presidential election, candidates Mitt Romney and Barack Obama make their last appeals to voters.

Launch slideshow

In Ohio’s Senate contest, Democratic Sen. Sherrod Brown leads Republican Josh Mandel by five points among likely voters, 50 percent to 45 percent.

And in Florida’s Senate contest, Democratic Sen. Bill Nelson leads Republican Connie Mack by nine, 52 percent to 43 percent.

The NBC/WSJ/Marist poll of Florida was conducted Oct. 30-Nov. 1 of 1,545 likely voters, and it has a margin of error of plus-minus 2.5 percentage points.

And the survey of Ohio was conducted Oct. 31-Nov.1 of 971 likely voters, and it has a margin of error of plus-minus 3.1 percentage points.