A senator serves in the US Senate, the upper chamber of the Congress. Senators must be 30 years of age before taking office. They also must be a citizen of the U.S. for nine years and reside in the state that they represent. Senators serve six-year terms. The primary responsibilities of a senator includes: legislation, government oversight, approving presidential appointees, approving foreign treaties, and trying the president during the impeachment process. They also work on committees and meet with lobbyists, whose job it is to convince congressmen to support a particular piece of legislation. The responsibility of legislation and government oversight are duties shared with the House of Representatives, the lower chamber of the Congress. In total, there are 100 senators, two for each state.