Call them "born again" undecideds: Republicans exploring bids for the presidency in 2012 have ramped up their religious fervor and sharpened answers to questions about faith in an effort to court social conservative voters in key early primary states.
"I believe in God. I am Christian. I think the Bible is certainly, it is 'the' book," real estate mogul Donald Trump told the Christian Broadcasting Network last week after catapulting to second place in a poll of unofficial GOP presidential contenders.
But as voters begin to scrutinize the lives of a wide-open field of unofficial GOP presidential contenders, several personal histories might raise red flags in some religious circles.
Former Minnesota Gov. Tim Pawlenty's transition from the Catholic Church to evangelical Protestantism in the 1990s after marrying his wife, Mary -- a move he explains in his book "Courage to Stand" as an effort to "merge my faith and my church life" -- could hurt his appeal among some Catholic primary voters, several Catholic political activists said.
"To the degree that Catholics know about Pawlenty's conversion, they won't like it," ABC News political contributor Cokie Roberts said.
Meanwhile, former House Speaker Newt Gingrich might have curried favor among Catholics with his high-profile conversion to the church two years ago, leaving his Baptist roots behind. Some observers believe the shift, which came as he also sought public forgiveness for his marital infidelity, could also help him among Christians in general by demonstrating that he has been spiritually reborn.
"Newt's conversion could affect his candidacy in an indirect way by helping him explain some of his decisions," Brian Burch, president of CatholicVote.org, said of Gingrich's three marriages and confessed affair with a hill staffer, who later became his wife.
Trump has also been put on the spot by Christian evangelicals for his two failed marriages. "I'm a very hard worker, and I've always said it's very difficult for a woman to be married to me because I work all the time," he told CBN's David Brody when asked to explain why they failed.
"Mormonism for most conservative Christians who have read about Mormonism, who have investigated it, would be in a different category," said Chuck Hurley, president of the Iowa Family Policy Center, who has begun sizing up the potential nominees making swings through the state. "I have met people who call themselves Mormon that I think are pretty biblically orthodox, but the deeper you look into the roots and tents of Mormonism, the more divergence you find."
Religious leaders in Iowa and South Carolina, where evangelicals wield significant influence in caucuses and primaries, praised the leading likely candidates for their testimonies of faith and orthodox positions on issues such abortion and same-sex marriage.
But when it comes down to picking a nominee, they say, they're really looking for genuine religiosity, which may be a problem for some Republican hopefuls who've stumbled along the road to Damascus.
"We will not just go by what they say and what we see," Hurley said. "It's much more important what they really, really believe. Do they walk the talk."
Looking for Religiosity
Hurley said he recently spent nine hours one-on-one with possible presidential contender and Tea Party favorite Rep. Michele Bachmann of Minnesota. And while he wouldn't comment on the appeal of her potential candidacy at an early stage, he said she set the bar high for meetings with other prospective candidates seeking to do well in Iowa.
"It's going to boil down for a lot of people to whether they think a candidate is genuinely committed to faith," said Steve Scheffler of the Iowa Faith and Freedom Coalition. "Do they have a deep faith, did their religious principles also guide their public policy decisions in the past?
"I'm encouraging people not just to ask the generic questions on the social issues, but actually come up with tough questions so they can't just tell you what you want to hear," he said.
Religious conservatives admit that measuring religiosity is subjective, but offered a litany of factors beyond denominational labels and church affiliation that they find important, including regular public references to devotion to Jesus Christ, a record of moral personal behavior, scrupulous worship attendance and powerful adult spiritual conversion stories.
"For some people, the labels might be a factor," Tom Chapman of the Iowa Catholic Conference said, "but I think more importantly they're looking at the person ... and here in Iowa, they expect a retail-type campaign that allows them to meet the person at some point."
The biggest hurdles may be faced by the two potential Mormon candidates -- Romney and outgoing U.S. Ambassador to China Jon Huntsman. Thirty-five percent of Americans from across the political spectrum said in 2007 ABC News-Washington Post poll that they'd be less likely to support a presidential candidate who's a Mormon.
But experts say that sentiment could be changing, similar to a shift in public opinion toward Catholicism and politics that has evolved since more than 50 years ago.
"There's no systematic evidence that Americans have moved beyond their aversion to Mormonism, but my intuition is that it might be less problematic for Mitt [Romney] the second time around," said John Green, an expert on religion and politics at the University of Akron and senior fellow with the Pew Forum on Religion and Public Life.
And, Green said, while stances on economic and social issues have historically trumped specific religious affiliations in GOP primaries, a particularly large field of more than five candidates could mean denominational differences will be in play.
"In states like Ohio and Pennsylvania, which have significant conservative Catholic populations, it's possible religious affiliation alone may make a small difference," Green said. "If you've got five or six candidates or more, then very marginal changes within these religious voting blocs could be the difference between winning or losing a primary."