Illinois Senator Scott Lucas, although serving only two terms in the Senate, quickly ascended to the top of his party's leadership. Elected to the Senate in 1938, Lucas chaired the Committee to Audit and Control the Contingent Expenses of the Senate before being elected Democratic Whip in 1946. When Majority Leader Alben Barkley was elected Vice President in 1948, Lucas was unanimously chosen to be the new Leader. Over the next two years, Lucas struggled to unite members of his party who were at odds over the enactment of President Truman's Fair Deal and civil rights policies. He became one of the earliest critics of Senator Joseph McCarthy's anti-Communist crusade, and found himself targeted by McCarthy during his 1950 reelection bid. Lucas' inability to adequately discredit McCarthy's accusations, coupled with his strong connections to an unpopular Truman administration, resulted in his defeat by Everett M. Dirksen.

In 2006, the U.S. Senate Commission on Art unveiled a mural depicting the authors of the Connecticut Compromise–Roger Sherman and Oliver Ellsworth. The mural, painted by Bradley Stevens, is affixed to the wall of the Senate Reception Room.

The Senate president pro tempore is one of our national legisla- ture's three constitutionally mandated officers, along with the vice president and Speaker of the House. The president pro tempore is authorized to preside over the Senate, sign legislation, and issue the oath of office to new senators. Pro Tem: Presidents Pro Tempore of the United States Senate Since 1789 traces the development of the office in four brief essays and features biographical profiles and photographic images of its 87 occupants. Pro Tem offers stories that demonstrate how much the Senate has changed throughout its long history, while striving to maintain the ideals of its 18th-century creators.