The party leadership of the United States Senate refers to the officials elected by the Senate Democratic Caucus and the Senate Republican Conference to manage the affairs of each party in the See. Each party is led by a floor leader who directs the legislative agenda of his caucus in the Senate, and who is augmented by an Assistant Leader or Whip, and several other officials who work together to manage the floor schedule of legislation, enforce party discipline; oversee efforts to elect new Senators, and maintain party unity.
The titular, non-partisan leaders of the Senate itself are the Vice President of the United States, who serves as President of the Senate, and the President pro tempore, the seniormost member of the majority, who theoretically presides in the absence of the Vice President.
Unlike committee chairmanships, leadership positions are not traditionally conferred on the basis of seniority, but are elected in closed-door caucuses.
Since January 3, 2015, the Republican Party has constituted a majority in the United States Senate.
Since January 3, 2015, the Democratic Party has constituted a minority in the United States Senate.