In the United States, a contingent election is used to elect the president or vice president if no candidate receives a majority of the whole number of electors appointed. A presidential contingent election is decided by a special vote of the United States House of Representatives, while a vice-presidential contingent election is decided by a vote of the United States Senate. During a contingent election in the House, each state delegation votes en bloc to choose the president instead of representatives voting individually. Senators, by contrast, cast votes individually for vice president.
The contingent election process is specified in Article Two, Section 1, Clause 3 of the United States Constitution. The procedure was modified by the Twelfth Amendment in 1804, under which the House chooses one of the three candidates who received the most electoral votes, while the Senate chooses one of the two candidates who received the most electoral votes. The phrase "contingent election" is not in the text of the Constitution but has been used to describe this procedure since at least 1823.