But third-party candidates often raise issues not being discussed by other candidates, and over the long term they can influence Democrats and Republicans to shift their positions to attract more voters. And occasionally third parties have played a spoiler role on Election Day.
The most famous recent example is the impact of Green Party candidate Ralph Nader in the 2000 election. He won just 3 percent of votes nationally, but in Florida, where the race between Democrat Al Gore and Republican George W. Bush was determined by a margin of just 537 votes, Nader won more than 97,000 votes. Without Nader on the ballot, it’s likely that Gore would have won enough Florida votes to swing the state into his column—pushing him over the 270 electoral votes needed to clinch the presidency (see “Electoral College").
This year would seem to offer third parties another opening. According to a recent survey by the Pew Research Center, only 40 percent of Republicans say they’re content with Trump, and only 43 percent of Democrats say they’re satisfied with Clinton—both historic lows for major-party candidates heading into the general election. That helps explain why Johnson, the Libertarian, is polling around 10 percent, and support for Stein, the Green Party candidate, is about 5 percent. (McMullin, the independent, was too new to the race at press time to show up in most polls.)
While these candidates are unlikely to defeat Trump and Clinton, some experts believe that after the election there’s potential for a new major party to emerge. The Republican Party has been intensely divided over Trump’s nomination, leading to speculation that it could splinter.
“Who knows what will happen after November,” says Larry Sabato, director of the Center for Politics at the University of Virginia. “When a major party falls apart and cannot reunify, then inevitably you’re going to have a new major party form. Our system depends on it. We need two strong parties.”