But evangelicals are among the country's most politically conservative voters, and "they're going to hold their nose and vote for Romney. They're certainly not going to join the Obama campaign," said Patrick Mason, author of "The Mormon Menace: Violence and Anti-Mormonism in the Postbellum South."
Anderson, the pollster, said his research has found that evangelicals know more than other groups about what Mormons actually believe, and despite their religious differences tend to view Mormon values as positive.
"Is the bigger problem for Romney not evangelical Christians, but more secular voters who are skeptical of what Mormonism is, or just ignorant?" Anderson asked.
Perhaps it is just their growing hostility to religion in general, Mason said. "Mormonism becomes the lens through which they can paint their critique."
Regardless, the Romney campaign "would be crazy if they didn't have a plan in place already" to deal with Mormon bias, said Mark Noll, a University of Notre Dame historian who wrote "God and Race in American Politics," ''just like Obama's people are just dusting off whatever they had ready in 2008."
In 2008, racial issues threatened to torpedo Obama after the emergence of militant pro-black sermons by his former pastor, Jeremiah Wright. Obama defused the issue with a major speech on race, but the Wright connection fed a GOP narrative that Obama was not "one of us." Democrats labeled such statements coded language that appealed to racial prejudices.
In the final stages of his losing campaign, McCain declined entreaties from some advisers to use Wright's sermons to attack Obama.
"John McCain, whatever else you want to say about him, did not use all the racial weapons he could have used," said Randall Kennedy, a Harvard Law School professor and author of "The Persistence of the Color Line: Racial Politics and the Obama Presidency."
"Well, McCain lost," Kennedy continued. "I can't help but think that this time around, if there is anything that could plausibly be used, no matter how ugly, it will be used. So I anticipate a very messy, ugly campaign."
"I hope I'm wrong," Kennedy said, "but I expect it to be worse."
- Here's a quiz to test your Star Wars...
- LA man builds small home for homeless lady
- Report highlights earth-shattering increases...
- Britain's new princess can't expect...
- Have you seen 'Age of Ultron'? Here are 50...
- 'Avengers' sequel is second biggest US opener...
- Defending the Faith: Going up to Jerusalem
- Vonn says relationship with Woods is over
- Vermont Sen. Bernie Sanders: 'I am... 41
- Rage to relief in Baltimore as 6... 40
- Defending the Faith: Going up to Jerusalem 30
- Former tech executive Carly Fiorina... 17
- Governor, legislators leave 'baggage'... 14
- More Americans spending at least half... 13
- Famed neurosurgeon Ben Carson announces... 11
- Latest on police-custody death: 53... 9