He was reelected in 1946 and 1952 and served from December 7, 1944, to January 3, 1959. He served as chairman of the Senate Committee on Labor and Public Welfare (1953–1955), and co-authored the Smith–Mundt Act to specify the terms in which the United States government can engage in public diplomacy. He was not a candidate for renomination in 1958, but served as a special consultant on foreign affairs to the US Secretary of State from 1959 to 1960. Smith voted in favor of the Civil Rights Act of 1957.