Following the conviction of two senators on charges of corruption, novelist David Graham Phillips began a nine-part series of articles titled "Treason of the Senate." Publishing his articles in Cosmopolitan magazine, Phillips argued that large corporations and corrupt state legislators played too large a role in the selection of senators. The articles attracted a wide audience, but Phillips' reliance on innuendo and exaggeration soon earned him the scorn of other reformers, including President Theodore Roosevelt who coined the term "muckraker" to describe this kind of sensationalist journalism. Nonetheless, the series intensified pressures to establish the direct popular election of senators.

Meeting at Congress Hall in Philadelphia, Pennsylvania, the Senate temporarily abandoned its practice of conducting business behind closed doors while it considered whether or not to seat one of Pennsylvania's senators. Although, Albert Gallatin already had taken his Senate oath, senators questioned whether the Swiss-born senator had been a U.S. citizen for the constitutionally required nine years. To avoid public criticism in Gallatin's home state, senators determined the case should be resolved in full public view. They also decided to permanently open legislative proceedings. On February 28, 1794, by a two-vote majority that included Pennsylvania's other senator, the Senate denied Gallatin his seat.

During a time of badly strained relations between the president of the Senate's majority party, senators adopted a rule of requiring referral of all nominations to committee prior to consideration by the full Senate. At the same time, President Andrew Johnson's decision to remove from office Secretary of War Edward Stanton, which angered the majority of Republicans, prompted the Senate to adopt a resolution denying the president such power without the consent of the Senate. Three days later, the House of Representatives impeached Andrew Johnson. On May 16, 1868, the Senate acquitted the president by falling one vote short of the required two-thirds majority to convict.

Vice President John Adams led the entire Senate in a visit to President George Washington to offer congratulations on his 59th birthday. Decades later, on February 22, 1862, as a morale-boosting gesture during the darkest days of the Civil War, the Senate and House of Representatives met in a joint session to hear Secretary of the Senate John W. Forney read Washington's famous 1796 farewell speech. Twenty-six years later, on February 22, 1888, the Senate began an annual tradition that continues today. Each year, on or near the first president's birthday, a senator reads Washington's Farewell Address in the Senate Chamber.

Senator Alben Barkley (D-KY) resigned his post as majority leader after President Franklin Roosevelt vetoed a tax bill against Barkley's advice. The majority leader charged that the president's characterization of the bill as tax relief for the greedy was a "calculated and deliberate assault on the legislative integrity of every member of Congress." Following Barkley's "farewell" speech, the Senate gave him a boisterous standing ovation. Within minutes of receiving his letter of resignation, the conference of Democratic senators unanimously reelected him as their leader. Barkley served 12 years as Democratic floor leader, from 1937 to 1948, when he became vice president.