Clarence William "Bill" Nelson (born September 29, 1942) is the senior United States Senator from Florida, in office since 2001. A member of the Democratic Party, Nelson served in the Florida House of Representatives from 1972 to 1979, in the United States House of Representatives from 1979 to 1991 and as Treasurer and Insurance Commissioner of Florida from 1995 to 2000. In January 1986, Nelson became the second sitting member of the United States Congress to fly in space.