It's an issue that has been popping up recently in South Carolina, a primary state that is home to many evangelical voters and one that Romney has visited often in recent months.

"A presidential contest is a leadership test, not a religious one," McCain spokesman Danny Diaz said Tuesday when asked whether the senator denounces such attacks.

South Carolina state Rep. Gloria Haskins, who backs McCain, has raised concerns about the Mormon faith in media interviews. And The State newspaper in Columbia, S.C., reported last month that the McCain camp once circulated comments from evangelical leader James Dobson questioning any presidential candidate who is a member of The Church of Jesus Christ of Latter-day Saints.

"I don't think that I could see someone who is a member of a faith so contrary to my faith having my support," Haskins said in an Associated Press story in January.

Haskins - who has endorsed McCain but is not a paid staffer or spokesperson for the campaign - told National Public Radio earlier this month that Romney's Mormon faith is a "big thing" for her.

"Because, again, his faith is inconsistent with my faith," she said. "His faith is consistent with the Book of Mormon; my faith is consistent with God's word, the Bible. And they're not compatible."

Many evangelicals view the LDS religion with hesitation, mainly because the faith believes in scriptures beyond the Bible and because Mormons believe in modern-day revelation. South Carolina hosts the third primary in the party nomination process and is considered part of the religious Bible Belt.

Like McCain, former New York City Mayor Rudy Giuliani, also a GOP front-runner, has said there shouldn't be a religious litmus test.

In an interview this month with conservative radio host Hugh Hewitt, who is writing a book called A Mormon in the White House?, Giuliani was asked whether Romney will get any "evangelical blowback" because he's Mormon.

Giuliani responded that America is "way beyond that." The issue, he said, will be more about "how have you performed in public office, what have you done, have you acted as a fair, impartial person in dealing with people of all different religions or whatever. And if that's the case, those are the issues, not is what is someone's religion, but how have they acted."

Romney's campaign declined comment.

But even his wife, Ann Romney, recently joked that Romney was the only frontrunner who has had only one wife - a stinger directed at McCain and Giuliani, who no longer are married to their first wives.

And in September, Cyndi Mosteller, the GOP chairwoman of Charleston County, S.C., and a member of McCain's steering committee in 2000, "bombarded" Romney with questions about blacks and polygamy after a party meeting, according to a report in the National Review. The LDS Church did not allow black men to hold its priesthood until 1978.

Of course, a candidate really can't control supporters in such a large campaign, says Allan Lichtman, a professor of history at American University in Washington, D.C., and a presidential elections expert.

"It's impossible," Lichtman says, "especially when running a presidential campaign all over the country and you're as well known as McCain."

History has shown that to be true. McCain was angered himself in 2000 when he believed his opponents were spreading rumors about him fathering an illegitimate black child. Actually, his daughter, Bridget, was adopted from Mother Teresa's orphanage in Bangladesh. Then-Texas Gov. George W. Bush went on to beat McCain in that primary race.

When Herbert Hoover ran against Al Smith in 1928, Smith was the first Catholic candidate and Hoover supporters often attacked Smith's religion, Lichtman says. Hoover couldn't control his supporters no matter how hard he tried, Lichtman added.

On the other side, he says, it's right for Romney's supporters to complain about such comments against his Mormon faith.

"Every candidate who's been attacked like that from Al Smith on has said the same thing," Lichtman says.

tburr@sltrib.com