Comedian Jon Stewart highlighted that change in Republican minds recently while noting that Texas Pastor Robert Jeffress, who had once dismissed Romney's Mormon faith as a "cult," now argues that there's "every reason to support Mitt Romney."
"Simple math," Stewart joked in mimicking Jeffress' change of heart. "I hate Barack Obama more than I love Jesus."
Gallup first polled on whether Americans would vote for a Mormon when Romney's dad, George Romney, sought the White House in 1967. Back then, 17 percent of all voters (and 13 percent of Republicans) said they wouldn't vote for a Mormon commander in chief.
Overall wariness about a Mormon presidential candidate has fluctuated a bit in the 45 years since, with some polls showing a quarter of Americans opposed and others stretching higher. Republicans have varied in their stated angst about an LDS nominee, but never to as low as now.
Evangelical voters had backed other contenders Rick Santorum, Newt Gingrich, Rick Perry in the Republican primaries, but "they're all swinging over" to Romney now that he's the nominee, says Frank Newport, editor in chief of Gallup.
"People who have a strong party allegiance will, in some instances, hold their noses and vote for that nominee," Newport says, "particularly when [that nominee] is opposed to someone they don't like, which is certainly the case with Republicans and the current incumbent."
Voter thoughts toward supporting women, black and Jewish candidates have changed dramatically through the decades. In 1937, for example, a third of Americans said they would vote for a woman for president. That number shot up to nine in 10 Americans in the 2000s.
Voter objections to a Mormon White House hopeful, though, have averaged 18 percent from the 1960s to now in Gallup surveys with the exception of the latest Republican bloc.
Newport says voters often think of a specific presidential candidate when asked about gender, religion or race.
"The [Mormon] question had no mention of any particular person," he says, "but I think a lot of Republicans hearing the question said, 'Sure, no problem' because they were thinking in their own minds it was Romney and they'd certainly want to vote for their party's nominee."
In fact, for the first time ever on the question, zero percent of Republicans in the June survey said they didn't know or were unsure of their answer on whether they'd vote for a Mormon president.
"Increasingly, people are aware that Romney is Mormon," says Quin Monson, director of Brigham Young University's Center for the Study of Elections and Democracy. "It's probably a function of people who are more partisan who are aware. You've got some Republicans who are not very open to a Mormon who are reconsidering now that their party has nominated a Mormon."
Translation, GOP disdain for Obama could be wiping away the fear of what church a potential Republican replacement attends.
With the exception of a major speech he gave in December 2007 detailing how LDS leaders wouldn't dictate his actions as president, Romney has largely avoided talk about his faith one shared by a mere 2 percent of Americans.
He mentions God in stump speeches and occasionally cites the Bible but hasn't been as open to talking about his belief in the Utah-based faith's signature scripture, the Book of Mormon, or other LDS theology.
Monson, himself a Mormon, doesn't think Romney has done much to prompt the change in those now willing to vote for a Mormon.
"He's benefited from the run-up to the nomination," Monson says. "It was a monumentally weak field, and there is an incumbent Democrat that Republicans love to loathe. That's allowed him to make it through the nomination gantlet."
The key to all polls on the Mormon question may be how independents view it. Republicans are expected to back the Republican nominee.
But, in the latest survey, 18 percent of independents said they would not vote for a Mormon, about the same number, give or take a few points, as all along. Nearly a quarter of Democrats (24 percent) said the same.
A Salt Lake Tribune national poll late last year showed 26 percent of U.S. voters were either "very" or "somewhat" uncomfortable voting for a Mormon for president.
Among Republicans, 14 percent were uncomfortable with the prospect of an LDS commander in chief, compared with 27 percent of independents and 36 percent of Democrats, according to The Tribune survey.
Brad Coker, managing director of Mason-Dixon Polling & Research, The Tribune's pollster, finds the shift in GOP thinking about an LDS president particularly interesting.
"All of a sudden they've done a 180 [degree turn] in three months," Coker says. "All of a sudden, Romney's not a Mormon anymore, he's a business guy. They start looking at every other aspect of his life and they suddenly could not care less about his religion. There may be a few out there holding out. There aren't many."
Of course, the ultimate poll the only one that counts will come on Election Day.