Each senator is a member of one of the two party conferences (also known as party caucuses), depending upon party affiliation. (Independent senators decide which major-party conference to join.) Party conferences elect floor leaders, determine many committee assignments, and set legislative agendas. The Democratic floor leader serves as chair of the party conference, but the Republicans—in a practice dating back to 1945—divide those duties, electing one person to serve as conference chair and another to serve as floor leader.