Three figures highlight the predicament Donald Trump and Hillary Clinton face in this presidential race. Clinton is viewed unfavorably by 53 percent, Trump by 61 percent of likely voters. Coupled with the 37 percent of likely voters who say they would consider a third party candidate, it's a mix that could spell trouble for the two major party candidates.

That's why it is important for both Trump and Clinton to try to prevent as many voters as possible toying with the idea of voting for a third party candidate from turning that thought it into reality. especially since the Libertarian candidate, Gary Johnson, and the Green Party candidate, Jill Stein, are faring unusually well in the polls with ten and four percentage points, respectively.

Trump and Clinton have two key paths to fend off disaffected voters from moving to a third party candidate. They can either try to persuade those voters to overcome their misgivings and convince them that they represent their best option. Given the deep-seated resentment many voters harbor against Clinton and Trump that seems difficult. Or they can appeal to disgruntled voters by acknowledging that they may not be their first choice, but that a vote for someone else would lead to an even worse outcome.

Who is hated the most?

This kind of voting - choosing a candidate other than one's preferred option - is called strategic voting. And experts expect that it could matter in this presidential race, particularly in competitive states where a few percentage points could be decisive.

Robert Shapiro, a Columbia University professor who specializes in political polarization, said that this year's race between two historically unpopular main candidates should be a boon for strategic voting. "It could boil down to which candidate people hate the most."

Strategic voting "will be a factor in this election," concurs Barry Burden, director of the Elections Research Center at the University of Wisconsin-Madison. First, he noted, because many voters are looking for an alternative to Trump and Clinton. And second, he added, because the third party candidates Johnson and Stein are seen as credible options by many voters.

Simply casting a ballot for a third party candidate who is more attractive than one of the main candidates, however, isn't strategic voting. Strategic voting is people pulling back from their top candidate and deliberately voting for their second or third choice instead. "They do this because they are concerned that voting for their top choice is not an effective way to see the person they want elected be elected," said Burden.

Strong Libertarian ticket

While both Clinton and Trump are strongly disliked by many Americans, the Republican presidential candidate is generally viewed negatively by slightly more people than his Democratic opponent.

What's more, in Gary Johnson and William Weld, both former Republican governors, Trump faces a strong and experienced Libertarian ticket that appeals not just to Libertarians, but also to many mainstream Republicans who do not want to vote for Trump. A sign of the Libertarian appeal is that even as the election approaches, Johnson, unlike many third party candidates, has not lost steam in the polls.

Clinton's third party opponent on the left, Jill Stein of the Green Party, presents less of a headache for the Democratic presidential candidate than Johnson does for Trump on the right side of the political spectrum. While Stein is attractive to the progressive wing of the Democratic Party and to many still disgruntled Bernie Sanders voters, left-leaning Democrats will think twice before actually casting a ballot for Stein, said Burden.

That's because, he elaborated, many older Democrats continue to be haunted by the 2000 presidential election. In that race between Republican George W. Bush and Democrat Al Gore, Green Party candidate Ralph Nader, who received 2.7 percent of the vote, is still viewed as having spoiled a Gore victory by many Democrats. Nader and others have disputed this interpretation.

Historic lesson

"There's a lesson out of that election," said Burden. "Democrats were really sour about Nader after the election was over and blamed him for spoiling it. And many vowed that they wouldn't vote for a third party candidate again."

As a result, "those progressives who are enticed by Stein are worried that voting for her could lead to a worse option which is Trump in office," said Burden. "And so especially in close and competitive states they will be coming back to Clinton as election day approaches."

Friction on the right

While many Democrats are aware of the calculus of strategic voting and may ultimately shy away from casting a ballot for their preferred candidate, "many Republican voters are less aware or less concerned of that because it hasn't been something that has hurt their party any time recently," said Burden.

"You have a lot of Republicans out there who say that they will vote for Clinton because they absolutely don't want Trump elected," said Shapiro. "You are not going to find disgruntled Democrats out there who will vote for Trump."

What helped Trump clinch the nomination - the fact that disappointment and division on the right side of the political spectrum is even greater than on the left - may now hurt his chances to woo back disgruntled voters. Bernie Sanders, Clinton's strongest opponent, finally came around to support her, at least nominally. Ted Cruz, Trump's strongest opponent, explicitly did not support the Republican nominee.

Given the strife on the right, it is essential for Trump - who is trailing Clinton in the polls - to try to keep Libertarian candidate Gary Johnson at bay if he wants to keep a somewhat realistic chance of winning the election alive. Notes Burden: "Keep the Libertarians out of the debates if possible and try to bring them on board. So far this hasn't happened."