AMHERST, Mass. – Donald Trump and Ben Carson have a dominating lead over the rest of the field of Republican presidential candidates, and should either of them drop out of the primary race the other stands to benefit the most, according to a new UMass Poll released Nov. 16 by the University of Massachusetts Amherst.

Overall, Trump leads the Republican field with 31 percent of likely Republican voters listing him as their first choice, based on a nationwide online survey of 318 likely Republican primary voters conducted by YouGov America under the direction of the UMass Poll from Nov. 5-13. Carson comes in second at 22 percent, followed by Senators Ted Cruz and Marco Rubio at 13 percent and 9 percent, respectively. No other candidate was able to garner 5 percent support.

The poll also asked the second choice preference among respondents, and 36 percent of Trump supporters named Carson as their secondary choice, while Trump is the second choice preference among 30 percent of those backing Carson, indicating that if one of those two candidates were to leave the race the other would benefit significantly.

“Trump and Carson continue to lead the way as they have for longer than many thought they would, but Cruz and Rubio are well positioned to take advantage if either or both of them falter,” said Brian Schaffner, director of the UMass Poll.

The poll, which also tallied support among confirmed registered voters, also asked respondents to indicate every candidate they were willing to support in their state’s primary, as well as every candidate for whom they would not be willing to vote. Over half of Republican likely voters said they would be willing to support Carson and Trump. Jeb Bush attracted the most opposition among Republicans, with half of all respondents indicating that they would not be willing to vote for him. Other candidates attracting high levels of opposition included Sen. Lindsey Graham, George Pataki, Gov. Chris Christie and Jim Gilmore.

“These are frightening numbers for Bush,” said Raymond La Raja, associate director of the UMass Poll. “More than half of registered primary voters said they would not be willing to vote for him under any scenario. No other top-tier candidate faces this wall of unconvinced voters. Bush may think his campaign treasury will help him outlast other candidates, but that strategy seems implausible if voters do not list him as their second or third choice.

“However, Carson, Rubio and Cruz look well positioned right now,” La Raja continued. “As other candidates leave the dance floor and disappoint supporters, they are the next most attractive dance partners.”

“This poll is more evidence of the anti-establishment mood in the Republican electorate—Republican voters seem strongly opposed to nominating another career Republican party leader,” Schaffner added.

While Trump leads the poll, he also draws more opposition than any of the other frontrunners—nearly one in three Republicans say that they would not vote for him.

“Trump appears to have flat-lined,” La Raja said. “He needs to knock out Carson and Cruz to move forward. But his persuadable voters are fewer than other insurgent candidates. At least one-third of Republican primary voters said they would not consider voting for him.”

Likely Republican voters also said that Trump (40 percent) and Carson (24 percent) would have the best chances of winning a general election campaign.

“For supporters of Trump and Carson this is not just a protest vote,” said La Raja. “They actually think these candidates are best positioned to win the general election. That is fascinating given the weakness of their support among political elites and their total lack of government experience.”

The poll also surveyed 381 likely Democratic primary voters, and found that Sen. Bernie Sanders is struggling to gain any traction against Hillary Clinton. Clinton was the top choice among 63 percent of likely Democratic primary voters, compared to just 29 percent for Sanders.

Democrats also view Clinton as having the best chance of winning the general election, with 78 percent seeing her as the most competitive candidate to take on the Republican nominee, compared to just 19 percent for Sanders.

“Even many of Sanders’ supporters recognize that Clinton has the best chance of winning in November, and that is obviously a key part of her campaign juggernaut,” Schaffner concluded.

YouGov interviewed 1,224 respondents who were then matched down to a nationally representative sample of 1,000 American adults. The respondents were matched to a sampling frame on gender, age, race, education, party identification, ideology and political interest. Likely voters are respondents who said that they would definitely or probably vote in their state’s presidential primary or caucus. Confirmed registered likely voters are those likely voters who the UMass Poll directors were able to match to voter files as active registered voters. The margin of error among Republican likely primary voters is 6.4 percent, and the margin of error among Democratic likely primary voters is 6.0 percent.