Imagine this scenario. As expected, Hillary Clinton wins the Democratic Party's nomination for president, and Donald Trump wins the Republican nomination. However, disaffected Republicans run a third-party candidate. In the presidential election Clinton wins a plurality but not a majority of the popular vote. (A third-party candidate would likely hurt Trump more than Clinton.) Clinton likewise wins a plurality but not a majority of votes in the Electoral College. According to the Constitution, the House of Representatives then selects the president, with each state delegation possessing one vote. In this scenario the House of Representatives is the same heavily Republican body that now sits. The third party candidate, who finished second or even third in the popular vote, becomes president of the United States. Imagine the uproar, hopefully not a violent one, that would ensue such a subversion of the popular will.
Right now groups of Republicans are planning to bring about precisely this turn of events. Refusing to support Donald Trump, they want to make sure a Trump nomination does not destroy the Republican Party. Erick Erickson, founder of the conservative website "The Resurgent," laid out a framework for such a plan in an NPR interview this week. A Trump nomination, Erickson reasons, would discourage many Republicans from voting, harming other GOP candidates all the way down the ballot. Not only would a third-party candidate bring out Republican voters, she or he just might win a controversial election.
Ordinarily third-party and independent candidates do not heavily disrupt presidential elections. They may influence the final outcome by pulling more votes from one candidate than from another. People still debate whether Ralph Nader's 2000 candidacy pulled the election away from Al Gore to George W. Bush. Hanging chads aside, however, no third party candidate has turned the election over to the heavily partisan House of Representatives. That could happen this year.
The only thing voters can do to prevent such an outcome is to mobilize. They could mobilize to protect one another by rejecting third-party candidates. No such effort would eliminate support for such candidates, but it could prevent a third-party candidate from winning Electoral College votes. Alternatively, voters could prevail upon their House representatives to honor the plurality of electoral votes, should things come to that. I highly doubt such an effort would be successful.
If you find a House election of a candidate who finishes second or third in the Electoral College vote an ugly prospect, it has happened before. The 1824 election featured four candidates, all from the same party. With no Electoral College majority, the House elected second place finisher John Quincy Adams over Andrew Jackson, who had won a plurality of votes. Representative Henry Clay, who finished fourth in electoral votes himself, turned over his support to Adams. In what came to known as the "Corrupt Bargain," Adams appointed Clay as secretary of state.
Not only could it happen again, people are planning to make it so.