The contingent election process is specified in Article Two, Section 1, Clause 3 of the United States Constitution.
In 1800, Thomas Jefferson and Aaron Burr, the presidential and vice-presidential nominees on the ticket of the Democratic-Republican Party, received the same number of electoral votes.
In 1836, faithless electors in Virginia refused to vote for Martin Van Buren's vice presidential nominee, Richard Mentor Johnson, denying him a majority of the electoral vote and thus forcing a contingent election in the Senate for vice president; Johnson won the election handily.
The contingent presidential elections to date have been held in closed session, with the vote of each representative not revealed outside the House Journal.
[2] If no candidate for vice president receives a majority of the electoral votes, pursuant to the Twelfth Amendment, the Senate is required to go into session immediately to choose the vice president from the two candidates receiving the most electoral votes.
[7] Some academics and journalists have thought that the language in the Constitution about being elected by a "majority of the whole number of senators" makes it unlikely that the vice president could break a tie.
[9] The Constitution mandates that, "if there be more than one who have such Majority, and have an equal Number of Votes, then the House of Representatives shall immediately chuse [sic] by Ballot one of them for President."
Given the deadlock, Democratic-Republican representatives, who generally favored Jefferson for president, contemplated two distasteful possible outcomes: either the Federalists manage to engineer a victory for Burr, or they refuse to break the deadlock; the second scenario would leave a Federalist, Secretary of State John Marshall, as acting president come Inauguration Day.
[11] Over the course of seven days, from February 11 to 17, the House cast 35 successive ballots, with Jefferson receiving the votes of eight state delegations each time, one short of the necessary majority.
[9] The 1824 presidential election came at the end of the Era of Good Feelings in American politics and had four Democratic-Republican candidates who won electoral votes: Andrew Jackson, John Quincy Adams, William H. Crawford, and Henry Clay.
Clay subsequently threw his support to Adams, who was elected president on February 9, 1825, on the first ballot[12][13] with 13 states, followed by Jackson with seven, and Crawford with four.
Adams' victory shocked Jackson, who, as the winner of a plurality of both the popular and electoral votes, expected to be elected president.
Under the Twelfth Amendment, a contingent election in the Senate had to decide between Johnson and Whig candidate Francis Granger.
[14] Some members of Congress have proposed constitutional amendments to alter the contingent election process.
[2] Contingent elections for president were historically also present in the constitutions of various Latin American countries which were influenced by the U.S.