"As people become more educated, they will think more broadly than what the differences are," Hunter said. "If he stands for what many conservative Christians stand for in terms of pro-life, pro-marriage between one man and one woman, they will become more comfortable."

In contrast to some of his rivals, Romney has been married for 37 years to his wife, Ann. His Christmas card shows his five beaming sons, their wives and his nine grandchildren. He neither drinks nor smokes, and even shuns coffee. On occasions when others might swear, he talks about how "bloomin"' mad he is.

Richard Land, head of the Southern Baptist Convention's Ethics Commission, said he doesn't see Romney's Mormon faith as an insurmountable problem.

"I think his Mormonism is going to be a bigger problem with the 'unchurched' than the 'churched,"' Land said. "The unchurched are fairly distrustful of and sometimes hostile of the churched, and they look upon Mormons as, sort of, religion on steroids. The churched respect people who take their faith seriously."