Fewer than half of Democrats, 46 percent, were comfortable with a Mormon president, with 36 percent uncomfortable.
The poll also found that if respondents linked Mormons with a political party, it was almost always the GOP, though more than half said they were either unsure or felt most Latter-day Saints were largely unaffiliated.
Researchers say the results were likely affected by Mitt Romney's presidential pursuit. A Mormon and former Republican governor of Massachusetts, Romney is well known nationally, partly because he also ran for president in 2007-08.
"They were not just thinking of a Mormon in an abstract, but for at least some of these people they are thinking specifically of Mitt Romney," said David Campbell, co-author of American Grace and a political scientist at the University of Notre Dame who studies religion and politics.
That may explain why Republicans are much more willing than Democrats to accept an LDS presidential candidate. But Campbell, who is a Mormon, noted that the Tribune poll and other surveys have all found somewhere between a quarter and a third of respondents were uncomfortable with a Mormon candidate, indicating "this is a real attitude we are tapping into."
Romney faced opposition in his first presidential run from a vocal group of Baptist and evangelical Protestants, mainly in the South, who argued the Utah-based Church of Jesus Christ of Latter-day Saints is not Christian and, in some instances, called it a cult. Romney tried to quell the issue with a high-profile speech about his faith.
He has been much less likely to talk about the LDS Church in his current campaign, and the issue has appeared to lose steam, though some religious leaders and political operatives have made disparaging comments about the religion.
The Tribune poll shows that even 67 percent of white evangelicals were comfortable voting for a Mormon presidential candidate, and 25 percent were uncomfortable.
The survey, conducted Dec. 12-16 by Washington, D.C.-based Mason-Dixon Polling & Research, had a margin of error of plus or minus 3.1 percentage points.
It found a higher comfort level than the September survey by the Public Religion Research Institute. That poll found 53 percent of Americans were comfortable with a Mormon president, while 42 percent were somewhat or very uncomfortable. The institute's poll also found a much higher percent of white evangelicals (47 percent) who were uncomfortable with a Mormon in the Oval Office.
Sen. Orrin Hatch, R-Utah, said the Tribune poll shows Romney's Mormon issue will continue to fade.
"He paid the price the first time around," said Hatch, a Latter-day Saint and a Romney supporter. "[Voters] are now more familiar with him. I think they have gotten to know him. They realize he is a tremendous leader."
Tribune pollster Brad Coker didn't go so far as to say the issue is dead, but he agreed that it is far less likely to doom Romney's chances of becoming the GOP standard-bearer.
"I suspect, in certain states, being Mormon is not going to help him," he said. "But, when all is said and done, it is not going to cost him the nomination."
The Tribune poll also asked respondents what qualities without offering any possible answers made them comfortable or uncomfortable with Mormons. Of those who said they were comfortable, the most cited responses were "pro-family" and "friendly," both receiving about 20 percent. Others said Latter-day Saints are hard working and Christian.
Polygamy was the top complaint of respondents about Mormonism, garnering 28 percent. The tenet, discarded by the LDS Church more than a century ago, has remained a public relations headache for the faith, especially as separatist groups continue the practice.
"It is easy to see why some people who don't know any better might still have concerns about that," Hatch said. "But I think most enlightened people know the LDS Church would excommunicate people who practice polygamy."
Respondents who would be uncomfortable with a Mormon president also broached the LDS-Christian question, with 13 percent saying Mormons aren't Christians and 11 percent viewing them as members of a cult.
But even taken together, those concerns fell short of polygamy.
Respondents also mentioned four categories on political or social issues, totaling 37 percent, that made them uncomfortable with most Mormons, saying they are "too politically conservative" (16 percent), hold "outdated views on women" (12 percent), have "outdated views on race" (7 percent) and citing "their views on gay rights" (2 percent).
The margin of errors went up to 5 percentage points on the comfort question.
Romney appears to be the most "logical" GOP candidate to poll respondent Harold Maupin, a Republican from La Crosse, Ind. Maupin isn't enamored with Romney as a politician, but his hesitancy has nothing to do with the candidate's religion.
"I would feel every bit as comfortable voting for a Mormon," he said, "as I would for a Presbyterian or a Methodist or a Baptist."
Maupin has knowingly interacted with one only Mormon in his life, a bridesmaid of his daughter-in-law, and has picked up scant knowledge about the faith. But he has heard about polygamy.
"I knew at one point they were polygamists, but it isn't the law of the land so I assume that is relatively rare," he said. "And I assume it is not only associated with Mormonism."
Alice Ross, of Butler, Pa., has had Mormon missionaries visit her home and talked to Presbyterian pastors about LDS teachings. She believes members are "clean, immaculate people" with "very high moral standards."
But, besides polygamy, Ross is concerned about how well organized the faith is and the impact it could have on politics, which is why she would be very uncomfortable voting for a Mormon presidential candidate.
"They are a very strong movement in America," she said. "The president would make decisions based on his Mormon beliefs, and that would not be good."
Top LDS leaders issue a statement before elections encouraging their members to vote, while at the same time reaffirming the faith's political neutrality.
"Elected officials who are Latter-day Saints," according to the faith's website, "make their own decisions and may not necessarily be in agreement with one another or even with a publicly stated church position."
While the poll found that faith played an important role for 70 percent of likely voters, not everyone thinks it should. Ariel Kaplan, of Pembroke Pines, Fla., bristled at the poll questions.
"Nobody should make a decision for president thinking what religion they are," said Kaplan, a Democrat. "On the other hand, I don't think the president should make any decision based on his religion."
In analyzing the poll in its entirety, Coker said, "The overarching theme that comes through is a lot of people don't really know that much about the Mormon church."
An example is the poll question on partisan affiliation in which respondents had a hard time identifying which political party, if any, most Mormons were most associated with. The largest group, 38 percent, said they were unsure. After that, 34 percent tied them with Republicans and 25 percent said neither major party. Just 3 percent reported Mormons were more likely to be Democrats.
While the highest-ranking Mormon in the federal government is Senate Majority Leader Harry Reid, a Democrat from Nevada, most LDS politicians are Republicans.
"Apparently one Harry Reid doesn't outweigh a Mitt Romney, Orrin Hatch or Mike Lee," said Campbell, referring to Utah's two Republican senators.
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