Joseph Lieberman is an American politician and attorney who served as a United States Senator from Connecticut from 1989 to 2013. Initially a member of the Democratic Party, he gained national prominence as the party's nominee for Vice President in the 2000 election alongside Al Gore. After losing the election, Lieberman continued to serve in the Senate, where he became known for his centrist views and willingness to cross party lines, particularly on issues such as national security and energy policy.