权变选举

在美国，权变选举（或：临时选举；英语：Contingent election）是依据美国宪法第十二条修正案中提到的解决如果没有总统候选人获得过半选举人票的情况下，由众议院选总统，参议院选副总统程的程序。这种情况极为罕见，至今只发生过三次。触发这一选举程序的情形包括：

• 多名被选举人竞选，没有单一被选举人获得50%以上的绝对多数选举人票；
• 两名被选举人竞选，双方同时获得50%的选举人票。

1824年美国总统选举，
四位候选人中没有一人票数过半

美国宪法第十二条修正案中相关条文如下：

...The person having the greatest number of votes for President, shall be the President, if such number be a majority of the whole number of Electors appointed; and if no person have such majority, then from the persons having the highest numbers not exceeding three on the list of those voted for as President, the House of Representatives shall choose immediately, by ballot, the President. But in choosing the President, the votes shall be taken by states, the representation from each state having one vote; a quorum for this purpose shall consist of a member or members from two-thirds of the states, and a majority of all the states shall be necessary to a choice. And if the House of Representatives shall not choose a President whenever the right of choice shall devolve upon them, before the fourth day of March next following, then the Vice-President shall act as President, as in the case of the death or other constitutional disability of the President...

译文如下：

• ...获得总统选票最多的人，如所得票数超过所选派选举人总数的半数，即为总统。如无人获得这种过半数票，众议院应立即从被选为总统之人名单中得票最多的但不超过三人中间，投票选举总统。但选举总统时，以州为单位计票，每州代表有一票表决权。2/3的州各有一名或多名众议员出席，即构成选举总统的法定人数，选出总统需要所有州的过半数票。当选举总统的权力转移到众议院时，如该院在次年3月4日前尚未选出总统，则由副总统代理总统，如同总统死亡或宪法规定的其他丧失任职能力的情况一样...[1][2][lower-alpha 1]
  ——第8届美国国会，1803年11月9日