Clarence William "Bill" Nelson (born September 29, 1942) is the senior United States Senator from the state of Florida and a member of the Democratic Party. He is a former U.S. Representative and former Treasurer and Insurance Commissioner of Florida. In 1986, he became the second sitting member of the United States Congress to fly in space.
In 1972, Nelson was elected to the Florida House of Representatives. He was re-elected in 1974 and 1976. Nelson was elected to the U.S. House of Representatives in 1978. He served in the U.S. House from 1979 to 1991. In January 1986, he flew as a Payload Specialist on the Space Shuttle Columbia. After a failed gubernatorial race in 1990, he successfully ran for the office of Treasurer and Insurance Commissioner of Florida in 1994 and served for six years. In 2000, Nelson ran for U.S. Senate seat vacated by retiring Republican Senator Connie Mack. In the Senate he is generally considered a social moderate and economic liberal. He was re-elected in 2006 with 60 percent of the vote.