Specter passed the Pennsylvania Bar in 1956 and soon became a prominent lawyer in Philadelphia, eventually becoming District Attorney. He worked with the Warren Commission investigating the assassination of President John F. Kennedy. He became the Republican candidate for Senate in 1980 when the Republican incumbent, Richard Schultz Schweiker announced his retirement.
Specter won the election and was reelected in 1986, 1992 and 1998. He was chairman of the Select Committee on Intelligence from 1995, when the Republicans gained control of the Senate, until 1997, when he became chairman of the Committee on Veterans Affairs. He was chairman of that committee until 2001, when the Republicans lost control of the Senate, and became chairman again when they regained control in 2003. In 1998 and 1999 Specter criticized his own party for its impeachment of President Bill Clinton.