Who agrees with Ben Carson?

Republican presidential candidate Ben Carson spoke in Greenville, S.C.Richard Shiro/AP/File

Over the weekend, surging GOP White House contender Dr. Ben Carson said he didn’t think Islam was consistent with the US Constitution, adding he couldn’t support a Muslim for president.

His position, while out of step with the American public at large, is not unusual among Republicans. Less than half of Republicans are willing to vote for a Muslim president, as compared to 3 out of 4 Democrats, according to polling.

Would Americans vote for a Muslim president?

In a Gallup survey this summer, just 6 in 10 Americans said they felt comfortable voting for a Muslim candidate for president. That’s far less than the 74 percent who would back a gay or lesbian candidate, the 81 percent who could support a Mormon, or the 90-plus percent who said they could vote for a Jewish, black, Hispanic, or female candidate.

Beyond these headline numbers, though, there are stark differences between Democrats and Republicans. In fact, when Ben Carson said Sunday that he wouldn’t vote for a Muslim president, he was expressing the majority opinion within his party. Only 45 percent of self-identified Republicans told Gallup that they could vote for a Muslim.

How many Republicans think we already have a Muslim president?

At a New Hampshire rally last Thursday, Republican front-runner Donald Trump declined to correct a questioner who incorrectly claimed that President Obama is a Muslim. And judging from the polling, there may have been a lot of people in that room who agreed.

A recent survey by the respected but left-leaning Public Policy Polling found that a majority of Republican voters believe Obama to be Muslim. Polls from the Pew Research Center taken in 2012 have found a smaller, but still substantial number of registered Republicans with the same misapprehension.

Does this matter for the election?

Not directly, since there are no Muslim candidates vying for the presidency — and so far no claims that Hillary Clinton or Bernie Sanders are themselves Muslim.

But it’s yet another sign of the distance between the parties.

And beyond that, the fact that only 6 in 10 Americans — of all political stripes — are willing to support a Muslim for president gives a sense for how politically marginalized the Islamic community really is.