The 12 th Amendment to the Constitution provides backup, or standby, procedures by which the House of Representatives would elect the President, and the Senate the Vice President, in the event no candidate wins a majority of electoral votes. Although this procedure, known as contingent election, has been implemented only once for each offic e since the amendment's ratification, the failure to win an electoral college majority is theoretically possible in any presidential election. Some contingencies that might lead to an electoral college deadlock include: an election that is closely contested by two major candidates, leading to a tie vote in the electoral college; one in which multiple candidates gain electoral votes so that no candidate wins a majority; or an election where a number of electors sufficient to deny a majority to any candidate votes against the candidates to whom they are pledged. Any one of these developments would require Congress to consider and discharge functions of great constitutional significance. Moreover, the magnitude of these responsibilities might well be further highlighted by the fact that an electoral college deadlock would arguably lead to a period of protracted and contentious political struggle. This report examines constitutional requirements and historical precedents associated with the contingent election process. It also identifies and evaluates contemporary issues that might emerge in the modern context. The 12 th Amendment to the U.S. Constitution, with its provisions for contingent election, was proposed by Congress and ratified by the states in response to the constitutional crisis that marred the presidential election of 1800 and threatened the still-new American system of government under the Constitution. The Constitution's original provisions established a system of undifferentiated voting by presidential electors that proved unworkable after only four elections. Article II, Section 1 of the Constitution required each elector to cast two votes for his two preferred choices for President (at least one of whom was required to be from a different state than that of the elector) but none for Vice President. The candidate who received the most electoral votes was elected President, provided that the total number of votes also was a majority of the total number of electors, not electoral votes. The runner-up was elected Vice President. If no candidate received electoral votes equal to or greater than a majority of electors, or if there were a tie, then the House of Representatives would elect the President from among the five candidates who received the most electoral votes. Again, the runner-up would be Vice President. Voting in this original form of contingent election was by states, with each state's House delegation casting a single ballot. The problem was that the Philadelphia Convention of 1787 failed, or perhaps was unwilling, to anticipate the rise and rapid growth of political factions, or parties. Although the Constitution did not contemplate the existence of candidates for Vice President, by 1796, the nascent party organizations offered joint tickets for the two highest offices that included both a presidential and vice presidential candidate, running as a team. George Washington retired in 1796. During his second term, two political factions, the pro-administration Federalists and the anti-administration Jeffersonians, or Jeffersonian Republicans, began to assume most of the classic characteristics of political parties. In the presidential election to choose his successor in that year, both groups offered unified tickets with clearly identified party candidates for President and Vice President. In order to avoid a tie vote in the electoral college, and thus a second round, or contingent election by the House, party strategists planned that one or more of their electors would withhold a vote for the de facto vice-presidential candidate, and cast it for someone else—but neither party was able to "fine tune" the electors' actions to accomplish this goal. When the results were counted, the Federalists had won a majority of 71 electors to the Jeffersonians' 68. While Federalist electors all cast their first, "presidential," vote for their presidential candidate, John Adams, they split their second "vice presidential" vote among six different candidates. Similarly, the Jeffersonian electors all cast their first vote for Thomas Jefferson, but scattered their second vote among four vice presidential candidates. The result was that although Adams was elected chief executive with 71 electoral votes, his rival, runner-up Thomas Jefferson, was elected Vice President with 68 electoral votes. The deficiencies of the arrangement established in the Constitution became more than an annoyance in the election of 1800, when the two incumbents, President Adams and Vice President Jefferson, opposed each other for the presidency a second time. In a hard-fought contest, the Jeffersonian Republicans prevailed, winning 73 electors to the Federalists' 65. In a noteworthy omission, especially considering the election results in 1796, all the Jeffersonian electors cast their first vote for presidential candidate Jefferson, but all 73 also cast their second vote for Aaron Burr, his vice presidential running mate. The failure to cast at least one less vote for Burr was an oversight, but it resulted in an electoral college tie between the two, requiring contingent election. The House and Senate met in joint session to count the electoral votes on February 11, 1805. The tie vote, which had been known well in advance, was announced, and the House adjourned to its chamber to begin the contingent election procedure. The situation was complicated by the fact that the count session was conducted by the lame-duck Sixth Congress, in which the Federalists controlled the House of Representatives. After the extremely bitter campaign, certain Federalist Members were inclined to vote for Burr to thwart Jefferson. At the same time, some Jefferson supporters threatened to take up arms if he were denied the presidency. Alarmed equally by threats of violence and the prospect of Burr as President, Alexander Hamilton, former Treasury Secretary and a senior Federalist leader, intervened. He urged Federalist Representatives to put aside partisan rancor in favor of the national interest and vote for Jefferson. The first round of voting revealed that Hamilton's appeal had had limited effect: a number of Federalists had voted for Burr, leading to deadlock. Of 16 state delegations in the House, eight supported Jefferson, six Burr, and two were divided—the votes of nine states would be necessary to elect. Nineteen ballots were cast the first day, and the House returned to cast an additional 15 on February 12, 13, 14, and 16 (February 15 fell on a Sunday in 1801), but the state results remained unchanged. Meanwhile, behind the scenes, negotiations continued to break the impasse. On Tuesday, February 17, the House cast a 35 th ballot, which showed the same results as the preceding 34, but on the next round, a Federalist Burr supporter from Vermont cast a blank ballot, swinging that state into Jefferson's column and delivering him the presidency. With the shift in momentum, the previously divided Maryland delegation also switched to Jefferson, while Burr supporters Delaware and South Carolina changed their votes, moving those states from Burr into the divided column. The final tally was Jefferson, 10 states, and Burr, four, with two states divided. By the time the Seventh Congress convened, support was spreading for a constitutional amendment that would establish a separate electoral vote for President and Vice President. Federalist opposition prolonged debate over the proposal, delaying approval until the first session of the Eighth Congress, which convened on October 17, 1803, but on December 9 of that year the amendment was submitted to the states. The ratification process proceeded with notable speed for an era characterized by poor communications and state legislative sessions that were both short and infrequent. By July of 1804, 13 of the 17 states then in the Union had ratified the proposal, and on September 25 of that year, Secretary of State James Madison declared the new 12 th Amendment to be ratified, so that it was in effect for the 1804 presidential election, which followed within weeks. The Amendment made important changes in electoral college procedures. First, the electors continued to cast two votes, but they would henceforth cast separate ballots for President and Vice President, one vote for each office. This change was an implicit concession to the prevalence of unified party tickets for the two offices. Second, a majority was still required to win both positions, but reflecting the separation of votes for the two offices, it would be a majority of electoral votes, rather than electors. Contingent election procedures were retained largely intact, aside from two revisions. First, the amendment eliminated the provision that the electoral college runner-up would be Vice President; contingent election for that office was transferred to the Senate. Second, it reduced the number of presidential candidates eligible for consideration by the House in a contingent election from five to three. Finally, it established the same qualifications for Vice President as for President. Qualifications for the vice presidency had been deemed unnecessary by the Convention, since all contenders were candidates for the presidency, and were therefore required to meet that position's standards. In one sense, the 12 th Amendment has been a substantial success: its separation of presidential and vice presidential ballots has guaranteed that there will never be an exact repeat of the 1800 election. Much of the electoral stability achieved in the ensuing two centuries may also be attributed to the domination of American presidential politics by the two-party system, which was implicitly sanctioned in the amendment. Notwithstanding the complaints of would-be minor party or independent candidacies, the two-party system, in conjunction with the winner-take-all system of awarding electoral votes, generally delivers an electoral college majority to one ticket. One potential drawback is that it has also tended to deter presidential bids by independent candidacies or new parties, for better or worse. Contingent elections have been conducted only twice since ratification of the 12 th Amendment: for President in 1825, following the election of 1824; and for Vice President in 1837, following the election of 1836.