The two houses of Congress depend on many different types of leadership. The Constitution provides for presiding officers for both chambers: the Speaker of the House; the president of the Senate (who is the Vice President of the United States); and the president pro tempore of the Senate, who presides in the Vice President' absence.
Once political parties were established, their members in Congress formed party caucuses, each of which elected a chairman. In the Senate the caucus chairman often acted as a party floor leader. Over time the party leadership positions of majority and minority leader and majority and minority whip evolved as formal leadership posts. Leadership is also provided by the chairmen and ranking minority members of the House and Senate committees. Additionally, members of both Houses have formed blocs, or caucuses, united by region, race, or issues, whose leaders develop prominence and power within their chamber. Although leadership generally comes through seniority or election to a formal party post, strong, assertive, and charismatic personalities have also exerted influence and leadership over their colleagues even without holding a formal position.
see also Majority leader; Minority leader; President pro tempore of the Senate; Speaker of the House; Vice President; Whip
