Robert Carlyle Byrd was an American politician and musician who served as a United States senator from West Virginia for over 51 years, from 1959 until his death in 2010. A Democrat, Byrd also served as a U.S. representative for six years, from 1953 until 1959. He remains the longest-serving U.S. Senator in history; he was the longest-serving member in the history of the United States Congress until surpassed by Representative John Dingell of Michigan. Byrd is the only West Virginian to have served in both chambers of the state legislature and in both chambers of Congress.

The Democratic Caucus of the United States Senate, sometimes referred to as the Democratic Conference, is the formal organization of all senators who are part of the Democratic Party in the United States Senate. For the makeup of the 118th Congress, the caucus additionally includes three independent senators who caucus with the Democrats, bringing the current total to 51 members. The central organizational front for Democrats in the Senate, its primary function is communicating the party's message to all of its members under a single banner. The present chair of the Senate Democratic Caucus is Chuck Schumer of New York.