Polling suggests presumptive Republican nominee Donald Trump and presumptive Democratic nominee Hillary Clinton are the least popular nominees since 1992, when independent Ross Perot captured nearly 20 percent of the vote.
But this time around, no other candidates are polling above 10 percent, leaving voters with just two candidates who appear nationally competitive. Fewer than half of voters registered in either party are happy with their choices for president, with only 43 percent of Democrats and 40 percent of Republicans satisfied with the options, according to a recent Pew Research poll.
Forty-one percent of voters say neither of the major party candidates would make a good president. Nevertheless, neither Libertarian Party nominee Gary Johnson nor the Green Party's presumptive nominee, Jill Stein, are polling well enough to participate in the debates. Despite some Americans' hope for a more competitive independent candidate to appear, none have arisen.
Increased partisan polarization has left about 40 percent of each party completely committed to their party's nominee, says Lara Brown, the director of the political management program at George Washington University's Graduate School of Political Management, in an interview with The Christian Science Monitor.
"We don't have that type of independent thinking or thought among those who are activist partisans," she says. "They're focusing on making sure the other side doesn't win."
America's current political structure, especially the electoral college, stands in the way of a viable third party candidacy, Dr. Brown says. Former New York City mayor Michael Bloomberg considered an independent bid this cycle but decided that even if he won the most popular votes, no candidates would get an electoral college majority in a three-way race, sending the election to Congress.
The electoral college allows both of the major political parties to make the argument that voting for a third-party candidate could throw the election, Walter Stone, a professor at the University of California, Davis tells the Monitor.
"If you take away the winner-take-all aspect of the electoral college, at least the wasted-vote problem goes away in principle," he says. "It's very easy for the major party candidate who is threatened by the third party... to make the case that this is just going to help the worst candidate, and the more polarized the system is the worse the worst candidate looks to your potential supporters."
Partisan voters worry that voting for a third party candidate who may more closely align with their views may throw the election to the major-party candidate they like less, as many believe Ralph Nader did as the Green Party candidate in the 2000 election between Al Gore and George W. Bush.
The current ideological positioning of the two major parties leaves little room for a third-party option, says John Aldrich, a professor of political science at Duke University. Candidates running as populists have seen the most third-party success, such as Perot in 1992 and George Wallace in 1968. During the 2016 primaries, however, that lane was filled by Donald Trump on the right and Bernie Sanders on the left, blocking any possible populist third party bids.
By the time it became clear who the two nominees would be, filing deadlines to appear on the ballot were rapidly approaching. A very public effort to recruit a like-minded third-party option from the editor of the conservative publication The Weekly Standard, Bill Kristol, proved unsuccessful, leaving the voters with Trump, Clinton, Johnson, and Stein as the leading candidates.
When voters are presented with those four candidates, Johnson receives 6.7 percent, according to the most recent polling averages from RealClear Politics, while Stein receives 3.5 percent. Both numbers are well below the 15 percent threshold for debate entry.
"The debates would certainly raise viability," Dr. Stone, from UC Davis, says. "They convey a sense of legitimacy, so that would be crucial."
Publicity aside, lesser-known candidates' views can also present stumbling blocks. Johnson's libertarian ideals, for example, appeal only to about ten percent of the electorate, Aldrich estimates. Stone agrees that Johnson's policy positions prevent him from being a true contender.
Both Johnson, the former governor of New Mexico, and Stein, an activist and physician, are currently polling much higher than they finished when they ran in 2012, however. That year, Johnson finished with almost 1.3 million votes, just under 1 percent of the vote. Stein received 469,627 votes, or 0.36 percent of the total.
This year will likely be an above-average year for third-party candidates, Brown says. On average, they get less than 3 percent of the total vote, but it is feasible that Johnson and Stein could capture around 10 percent, collectively, she estimates. But the chances of a third-party candidate winning is stymied by current political polarization, combined with the structural challenges faced by the plurality electoral system which "fundamentally fosters two-party competition."
If a win by Hillary Clinton is widely expected as the election approaches, however, more members of the progressive left could vote for Stein, while more Republicans may decide to vote for Johnson.
"I really think the popularity of the third party candidates this time around as a protest vote – because that's likely what it would be – is really going to be more about how much do people feel the other race is already decided," Brown says.