Whips exist in both the United States Senate and the House of Representatives for each party. They're called the Majority and Minority Whips depending on which party has the most legislators during any given session.
The whip is responsible for ensuring that important votes have the desired outcome for their party on major issues. If, for example, legislators are undecided on how they'll vote on an issue, the whip from each legislator's party will try to persuade him or her to vote accordingly. (The whip cannot threaten or bribe anyone, just present reasons and arguments as to why a certain vote is desirable.) Whips also make sure that legislators are present for important votes.
In the Senate, the Majority Whip ranks third (or fourth) highest in the majority party. The Majority Whip is outranked by
- The Senate Majority Leader (also called Senate Floor Leader), who is a Senator elected by his or her party to serve as their primary spokesperson and to manage the legislative sessions. By custom, the Majority Leader gets priority when he or she wishes to speak during a legislative session.
- The President pro tempore, who presides over the Senate when the Majority Leader is absent. The phrase "pro tempore" literally means "for the time being" in Latin. This is mostly an honorary position and is often given to the majority senator who's held office the longest.
- The United States Vice President (who is called President of the Senate when he is acting in this capacity). Regarding the Senate, the Vice President has only one job: to break tie votes (which are rare). That said, most Vice Presidents usually only show up in the Senate chambers when they think a tie vote may be pending. If the Vice President is a member of the Senate majority party, the Majority Whip's leadership rank drops to fourth when the Vice President is in the Senate chamber.
Leadership roles in the U.S. House of Representatives are similar to those in the Senate, except that neither the Vice President nor any other member of the executive branch has authority. Instead, the Speaker of the House presides over the House of Representatives. It's said that the Speaker of the House is the third most important elected official in the U.S. because his or her responsibilities are vast, and after the Vice President, the Speaker of the House is next in line to succeed the president.