As voting begins in Iowa on Monday, many Republicans are debating the following question: Would Donald Trump or Ted Cruz be the more electable nominee in 2016?

To get a more structural understanding of this discussion, we posed the question to six of the country’s top political science professors.

Their answers were all over the map.

Two professors said Trump was the better general election candidate; two said Cruz was more electable; one weighed a number of factors but didn’t come down firmly in either camp; and a sixth suggested the whole exercise was futile.

What explains the division? Experts who thought Trump was more electable tended to emphasize the importance of demographics in elections, arguing that Trump would do a better job attracting some groups (nativists, older white voters) than Cruz.

By contrast, those who thought Cruz would have a better chance spoke more about the crucial role political parties play in American elections. They argue Cruz is more likely to have the full backing of the Republican Party if he becomes the nominee, so he is more likely to win a general election.

Here’s what these top political scientists had to say.

Why Trump is more electable

Lynn Vavreck, a professor of political science and communication at UCLA

Cruz is drawing his support in the primary mostly from the Tea Party and "strong conservatives," Vavreck said. These groups don’t exist in large numbers in the general electorate — meaning there’s not much more support Cruz could pick up after the primary.

Trump, meanwhile, is drawing his support in the primary from multiple parts of the electorate, particularly those with only a high school education and people with high levels of racial anxiety, according to Vavreck.

That does suggest the potential for a broader base, because these constituencies also exist outside the Republican Party, Vavreck said.

"If you think about that and project it onto the general electorate, there aren’t a lot of Tea Partiers and strong conservatives for Cruz to pick up in the general electorate. But there are a lot of people with high levels of racial anxiety among Democrats and independents," she said.

Vavreck didn’t say that this would mean Trump would necessarily pull away Democratic and independent voters if nominated. But the chance at least exists for him to do so, she said, and it simply doesn’t for Cruz.

Theda Skocpol, a professor of political science at Harvard

Trump fits the mold of a type of populism that has proven popular in Europe. That strategy might be replicable in America, Skocpol suggested.

"[His campaign is] a combination of nativism, with an assertion of hostility toward free trade to some degree, and a defense of the core social protections for elderly citizens," Skocpol said. "That’s a very popular combination in Europe."

Unlike Cruz, Trump has voiced support for some policies that break with conservative orthodoxy. Would that lead some Republicans to stay at home and refuse to vote for Trump if he’s the nominee?

Skocpol didn’t think so. She argued that with high levels of party polarization, Republican Party loyalists are almost certain to come back into the fold — even if it’s to support a candidate like Trump, whom they don’t agree with on every issue.

"The country is now very, very polarized — and it isn’t just elite polarization. It’s penetrated into the electorate," Skocpol said. "Over the course of a presidential campaign, party loyalists tend to come home."

Why Cruz is more electable

Seth Masket, an associate professor of political science at the University of Denver

Masket said he recognized that Trump is more moderate on some issues than Cruz. But while Cruz may have more extreme policy positions, he is the better candidate, because Trump could really drive away Republican elites and voters.

Masket pointed to several issues in particular on which this group regards Trump as fundamentally unreliable: the social safety net, the military, abortion, and taxes.

"A large number of more ‘establishment’ Republican elites may bolt the party and support a third party candidate should Trump win a majority of delegates. Even if that doesn’t happen, a sizable number of Republicans might simply not vote," Masket said in an email.

He didn’t argue that Cruz is a great general election candidate. But since Cruz has proven consistently conservative, he would at least be able to unite the Republican Party and ensure that its voters go to the ballot box.

"[Cruz] is basically in line with the party on most of its key issues," Masket said. "Nominating him could put them at a slight disadvantage due to his extremism, but there’s little chance of him actually splitting the party."

Alan Abramowitz, a political science professor at Emory

Abramowitz said he thought both Trump and Cruz would be flawed general election candidates.

But Trump would be the worse candidate — in part because he has already alienated a large number of minority voting groups, Abramowitz said. That would increase turnout in support of a Democratic nominee in a way Cruz might not.

"You’d get an overwhelming opposition from Latinos and nonwhites. I just don’t see how he could win a general election," Abramowitz said. "I’ve seen some people argue (Trump) could win over African-American voters — that’s totally ridiculous; that’s totally absurd. This is the guy who tried to accuse Barack Obama of not being a legitimate president."

Additionally, Trump is so disliked by many Republican officials that a significant number may "sit on their hands and even support Hillary Clinton," Abramowitz said. The Democrats could use Republican officials’ denunciations of Trump against the real estate mogul.

"I think (Trump) is a clever guy who has figured out how to appeal to a large segment of the Republican electorate," Abramowitz said. "But you can’t win a general election that way."

While Cruz may be ideologically extreme, Abramowitz argued that the Texas senator would at least be able to unify the Republican Party.

"With Cruz, it’s a little trickier because he’s much more disciplined, but he’s very extreme," he said. "He can make himself appear more likable, even though he’s detested by his colleagues and those who know him well."

Why it's a toss-up between Trump and Cruz

John Sides, a political science professor at George Washington University

Sides noted that there’s some research showing that ideological extremism can hurt presidential candidates’ chances.

"In general, more extreme candidates — at least relative to the relevant constituency — will get less vote share," Sides said in an email.

That would seem to hurt Cruz more than it would hurt Trump. But it’s not entirely clear that extreme policies really have that large of an impact.

"The question ... is how big the effect is," Sides said, pointing to research suggesting that "the effect of ideological extremity isn’t that large or robust."

There’s another problem in thinking that Cruz’s hard-line conservatism would hurt him in a general election more than Trump’s policy platform: Voters may be repelled by Trump for his extreme positions on specific issues — like immigration — even if his overall platform is ideologically inconsistent.

"Would [Trump’s] positions, or at least his rhetoric, on immigration or other issues ultimately end up being perceived as ‘too extreme’? That is an open question. If so, perhaps Trump would be penalized as much as Cruz," Sides said.

Beyond the two candidates' policy positions, Sides pointed to evidence that Trump may be more personally disliked than Cruz.

Citing Gallup data published by FiveThirtyEight’s Nate Silver, Sides noted that Trump is less popular than Cruz with Republicans, Democrats, and independents.

"The upshot: The ‘persona’ factor is, as of right now, a bigger problem for Trump than for Cruz," Sides said.

Why really anything could happen

Morris P. Fiorina, a political science professor at Stanford University

Fiorina said that it’s difficult to predict a candidate's viability this year. "We cannot predict the context in which the 2016 election will take place," he said.

Fiorina listed a number of unknown variables that may prove crucial in deciding the election: Islamic State terrorist attacks, the ups and downs in the stock market, the controversy over Hillary Clinton’s email server.

"Depending on what comes to pass, we could see one of them win," Fiorina said. "Or you could see them taking the Republican Party down in a landslide."