On June 27, 1844, vigilantes cornered a man who claimed to receive messages from God and gunned him down in an Illinois jail after his arrest.

At the time of his death, Joseph Smith Jr., founder of the Church of Jesus Christ of Latter-day Saints, was an announced candidate for president of the United States.

Today, 167 years later, as two of Smith's adherents eye the nation's highest office, religious discrimination remains an obstacle for Mormon political candidates for president and a vexation for church members.

Two Republican contenders, former governors Mitt Romney of Massachusetts and Jon Huntsman of Utah, have sought to downplay the prejudice in presidential politics.

But a potential problem is hard to ignore: More than 1 in 5 Americans say they would not vote for a Mormon -- a figure that has changed only slightly since the question was first asked in 1967, according to Gallup polls.

John Green, a political scientist at the University of Akron in Ohio, said he believes anti-Mormon votes in key primary states undermined Romney's campaign four years ago, and LDS candidates face similar challenges this year.

Dan Peterson, a Mormon and a professor at Brigham Young University in Utah, noted that slim margins decide presidential races in many states, and the anti-LDS factor looms in the background for Romney and Huntsman.

"Whether it will be fatal to their candidacies, I don't know," he said.

Mormons have run for president before: Sen. Orrin Hatch, R-Utah, fell short in 2000; Sen. Mo Udall, D-Ariz., was unsuccessful in 1976; and Romney's father, George, failed in 1968.

Still, history has a way of setting precedents while seating new presidents. At one time pundits said a divorcee could not win the nation's highest office, but Ronald Reagan disproved that , just as Barack Obama broke the color barrier three years ago.

Rep. Jeff Flake, R-Ariz., scion of a prominent LDS family, says Americans who claim they won't vote for a Mormon may relent once they enter polling booths, just as avowed anti-Catholics changed their minds and helped elect John F. Kennedy a half century ago.

"When you have so many other topics to worry about -- the economy and jobs -- I think people care much less about what church you go to," Flake said.

Left and right

Last month a Baptist minister in Texas, Robert Jeffress, reignited the political controversy by urging Christians not to vote for Romney because of his faith.

"Do we prefer somebody who is truly a believer in Jesus Christ," Jeffress asked, "or somebody who is a good moral person but he's a part of a cult?"

At LDS headquarters in Salt Lake City, media relations manager Erick Hawkins declined interview requests but said in email that the church "doesn't consider honest disagreements on theology to be anti-Mormon. We recognize there are distinct elements of our belief that are different from other Christian faiths. We also believe there is much we have in common and important efforts where we can work together."

But antagonism doesn't just come from the Christian right: Liberal Democrats are even more likely to reject an LDS candidate. In June, Gallup pollsters reported 27 percent of Democrats would not vote for a Mormon presidential contender, compared with 18 percent of Republicans. The poll's margin of error was plus or minus 4 percentage points.

Pundits note that Mormons are the most right-leaning major religious group in America: A January 2010 Gallup poll indicated that 6 in 10 describe themselves as conservative, especially on social issues, which may explain Democrats' hesitancy.

The Independent, a British newspaper, offered arms-length perspective on America's electoral and theological debate in a recent analysis that concluded: "Hostility seems entrenched across the political spectrum. Liberals cast Mormons as weird God-botherers who are constrained by abstinence. €1/8 Conservatives take issue with their theology."

Who are Mormons?

Church records show 14.1 million LDS members around the globe. Nearly 6 million of them are in the United States, about 2 percent of the population.

Yet many Americans know little of Latter-day Saints beyond stereotypes. They see young missionaries on bicycles, wearing white shirts and dark ties, proselytizing door to door. They tell pollsters that, in their minds, Mormons are associated with plural marriage -- a practice the church renounced more than a century ago.

The false image lingers in part from media depictions such as the fictional cable show "Big Love," about a polygamist sect in Utah, and the prosecution of Warren Jeffs, leader of the Fundamentalist Church of Jesus Christ of Latter Day Saints, which promotes plural marriage but is not affiliated with mainstream Mormonism.

The church's antidote to such perceptions: an ad campaign featuring happy, active and attractive people who smile into the TV camera and declare, "I'm a Mormon."

Although that PR blitz coincides with presidential campaigning, LDS authorities insist the promotion has nothing to do with elections -- and everything to do with combating negative images.

The church officially espouses a hands-off stance in partisan elections, but neutrality does not mean complete abstinence from politicking. LDS headquarters played a prominent role in passage of a Utah law against gay marriage.

"We feel strongly that there is a right and obligation of the church to contribute to discussions of social and moral issues like religious freedom, the protection of traditional marriage and immigration," said Hawkins, the LDS spokesman.

Is it bigotry?

The U.S. Constitution bans a religious test for any office, but that clause is aimed at government-imposed restrictions, not citizens' private votes.

So, the inevitable question: Is it wrong for citizens casting secret ballots to discriminate based on theology?

Former church members, often the most virulent LDS critics, argue that voters are justified in excluding LDS candidates whose faith might influence public-policy decisions.

Richard Packham, the 78-year-old president of the Ex-Mormon Foundation, writes that the church's "ultimate goal" is "to establish the Mormon Kingdom of God in America and to govern the world as God's appointed representatives."

"I love the Mormons and hate Mormonism," Packham told The Arizona Republic. "To me, the possibility that the Mormon church might control America is a frightening prospect."

Tricia Erickson, a bishop's daughter who left the faith, just published a book titled, "Can Mitt Romney Serve Two Masters?" Erickson casts the church as a sexist, racist leviathan striving to gain power through politics. And she contends that Romney or Huntsman, as members, would have a duty to "follow the prophet -- no matter what," giving allegiance to religion over country.

Jeff Lindsay, a Mormon scholar who prolifically defends his church on the Internet, says Packham, Erickson and other critics convey an "awful distortion" of LDS doctrine and practices.

"It's paranoia. It's not based on any example," Lindsay said. "There is plenty of room for decent people to disagree with us. €1/8 But when someone strives to stir up anger toward the church and relies on misinformation or half-truths, then I'm inclined to apply the anti-Mormon label -- especially when they do it for a living."

Church defenders point out that thousands of LDS members serve in public office without acting as church puppets, and critics are unable to identify Romney gubernatorial decisions that his religion dictated.

As Lindsay puts it, "The prophet has not been coming in and telling him how to vote."

Although Romney more recently has allowed others to rise in defense, during the 2007 campaign he delivered a pivotal speech to dispel public concerns: "No authorities of my church, or any other church, for that matter, will ever exert influence on presidential decisions," he declared. "Their authority is theirs €1/8 (and) it ends where the affairs of the nation begin."

Real Mormons

Outside the Mormon temple in Mesa, Ariz., Brittany Garner, a 22-year-old nurse, says she senses prejudice occasionally when people make fun of an LDS ban on alcohol or caffeine, but that it's probably no worse than ignorant comments directed at other religions.

"They just don't know," she said, shrugging. "They haven't read our literature or talked to a Mormon."

Janet Burgess of Gilbert, Ariz., says she believes she has been passed over for promotions because of her religion and denigrated in conversations, but bigotry is rare and rolls off her back.

"What really makes me laugh is when they say you're not a Christian," she adds. "I tell them, 'Wait a minute, we're the Church of Jesus Christ of Latter-day Saints. It's in our name.' "

Burgess believes a public backlash against those who spread intolerance may offer hope to Romney and Huntsman.

"I think this time around they won't have as hard a time," she says. "People are more educated now."

Wagner also reports for The Arizona Republic.