In 1955, Stan Kimmitt became liaison officer to the Senate for the secretary of the Army. In 1965 he left the Army at the request of Senator Mike Mansfield (with whom he had once taken a course on Far Eastern history at the University of Montana) and initially served as Mansfield's administrative assistant. Democrats elected him secretary for the majority in 1966. In that post he served as the principal floor assistant to the majority leader and was responsible for facilitating the work of Democratic senators, keeping them informed of the floor schedule, anticipating votes, and reporting to the leadership on the prospects of important votes. When Senator Mansfield retired from the Senate in 1977, Kimmitt challenged the incumbent secretary of the Senate, Francis R. Valeo, and was elected to replace him. As secretary of the Senate, Kimmitt was the Senate's chief administrative officer, supervising the staff on the Senate floor, including the parliamentarians, legislative clerks, executive clerks, and reporters of debates. Also the Senate's chief financial officer, he was responsible for a budget which in fiscal year 1980 topped $218 million, including the salaries of all senators and staff. He supervised a myriad of other offices ranging from the Stationary Store to the Senate Library.