• The Senate majority leader became an official position in 1920.salt lake city capitol image by Albo from Fotolia.com
  
  The Constitution does not mention political parties, so it certain doesn't mention party leaders. The two-party system that exists today evolved gradually over time and has dominated American politics for a variety of reasons. In the late 1800s, senators grouped themselves by political party to elect representatives for themselves on the floor. From this practice, the role of Senate majority leader, with its concurrent duties of setting the agenda on the Senate floor and speaking for the party and the institution, eventually became an official position in 1920.
  
  

Party Spokesperson

• Unlike the Speaker of the House, who is the presiding member of the House of Representatives, the Senate majority leader is merely the spokesperson for the majority party. The vice-president is actually the president of the Senate and the titular presiding member. As spokesperson for the majority party, the majority leader speaks on behalf of the party, and for the Senate as an institution, both on the floor of the Senate and in press conferences.
  
  

Agenda Controller

• By rule, the presiding officer of the Senate (usually the president pro-tempore) gives the majority leader priority in recognizing speakers on the Senate floor. This gives the majority leader effective control over the Senate's agenda. At all times, when the Senate is in session, the majority leader, or a designated senator, is present to fill this role to steer the body along the course of the majority party's legislative agenda and protect their rights on the floor. In fact, Sen. Robert Byrd, D-W.Va., called the right of recognition the majority leader's "most potent weapon." The majority leader can set time limits on debate and divide time between the parties through unanimous consent agreements.
  
  

Dealmaker

• Beyond controlling the agenda on the floor of the Senate, the majority leader also plays an important behind-the-scenes role. Though the majority whip does most of the actual work convincing individual senators to vote along with the party leadership's plan, the majority leader can be persuasive. Because much of crafting legislative consensus involves deal-making, the Senate majority leader is often in the best position to make or orchestrate deals. Together, the majority leader and the majority whip ensure enough members vote for the party's agenda.