The minority leader in U.S. politics (as well as in some other countries utilizing the presidential system) is the floor leader of the second largest caucus in a legislative body. Given the two-party nature of the U.S. system, the minority leader is almost inevitably either a Republican or a Democrat. The position could be considered similar to that of the leader of the opposition in parliamentary systems. In bicameral legislatures, the counterpart to the minority leader in the lower house is the speaker, and the majority leader is hence only the second-most senior member of the majority caucus. Contrastingly, in upper houses, the titular speaker is frequently a separately elected officer such as a lieutenant governor or vice president.
The minority leader is often assisted in their role by one or more whips, whose job is to enforce party discipline on votes deemed to be crucial by the party leadership and to ensure that members do not vote against the position of the party leaders. Some votes are deemed to be so crucial as to lead to punitive measures (such as demotion from choice committee assignments) for members who violate the party line; decisions such as these are often made by the minority leader in conjunction with other senior party leaders.
