The current front-runners for the Republican nomination are Mitt Romney and Newt Gingrich. Massachusetts man Mitt might seem a model candidate. Wears a suit well, can string two words together, never known to have enjoyed an extra-curricular romp. His major minus is his Mormonism.

"I challenge how a Christian could campaign for Mr Romney", declares TV pastor Robert Jeffress of Dallas on his website, Ye Shall Be My Witnesses.

True, Dallas is hardly a microcosm of modern America. As legendary New York writer Jimmy Breslin once remarked to Skins McCarthy at Lifford dog track (no, really), "The last Catholic seen alive in Dallas, Texas, was John Fitzgerald Kennedy." A dreadful slur on the decent Dallas majority, goes without saying. And hardly the main point, anyway.

The main point is: how many Republicans across the US would regard Mitt's membership of the Latter Day Saints as a barrier to giving him their vote?

In Christian perspective, Newt's candidacy has negatives, too. Last time he pitched for the presidency, Newt came a cropper after former wife, Jackie Battley, previously his high school geometry teacher and 15 years his senior, revealed that she'd woken from surgery for life-threatening uterine cancer to find Newt hovering at the bedside with divorce papers in hand, asking her to sign so he could marry Marianne Ginther, 15 years his junior, with whom, he confessed, he'd regularly been romping throughout Jackie's illness.

After a few years of re-marriage, it was so long Marianne. She fell ill with multiple sclerosis and was in Ohio to break the news to her mother when Newt phoned to confess he had been sleeping for the past six years with House of Representatives staffer Callista Bisek, 23 years his junior, and would like a divorce.

In a comeback statement this year, Newt accepted he'd done wrong by Jackie and Marianne and explained the circumstances whereby these misfortunes had arisen: "There's no question at times of my life, partially driven by how passionately I felt about this country, that I worked far too hard and things happened in my life that were not appropriate."

As Dominic Behan has observed, love of one's country can be a terrible thing.

Newt's marriage to Callista still seems solid. She is reportedly in robust health. Evangelical outlets were thundering just weeks ago that Newt's sexual misdemeanors should disqualify him from the race. But now the tide has turned.

Last month, top TV Christian Jerry Falwell Jr invoked the story of the five-times-married fallen woman who met Jesus at a well and was forgiven. "The woman at the well was fortunate she encountered Jesus that day instead of some of our evangelical brethren," snorted Jerry.

Newt seems even to have been forgiven for becoming a Catholic. Celebrity preacher Richard Lee told CNN last month that Newt, in spite of his new-found Romanism, remains "the only forceful Christian candidate who can at this point be elected".

Since the opening exchanges in the presidential battle, evangelical activists have successively backed Michele Bachmann, then Rick Perry, then Herman Cain as their first choice to face Obama.

But one by one the Prod champions made fools of themselves, leaving the trice-married RC as the sole Christian candidate.

Mormons might say they are Christians. Mitt has repeatedly, passionately, publicly accepted Jesus as the only saviour of mankind.

But that's not good enough for Revs Jeffress, Falwell and Lee. How can he be a Christian, they ask, when he believes that Jesus was born in Jerusalem?

The Book of Mormon, Alma 7:10, is explicit: "And behold, he shall be born of Mary, at Jerusalem which is the land of our forefathers..." The book mentions Jerusalem as the birthplace of Christ on 19 occasions.

Hardly crucial, it might be thought - wrongly. If you believe in the literal truth of the Bible, locating the birthplace of the Son of God six miles from scriptural Bethlehem is a damning error and a dead giveaway.

Fifty-two percent of church-going evangelicals don't believe that Mormons are Christian. And 20% of registered Republicans say they couldn't bring themselves to vote for a Mormon for president.

Thus, for a significant number of wing-ding evangelicals, the notion of Mitt Romney going head to head with Obama next November opens up a truly appalling vista - a contest for the presidency of the United States between a Mormon and a Muslim.

No matter what way you look at it: scary.