The idea of a Mormon president is as unpopular today as the proposition of a Catholic occupant of the White House was in 1959. Gallup  recently asked “if your party nominated a generally well-qualified person for president who happened to be Mormon, would you vote for that person?” One in four Democrats and one in five Republicans and Independents say they couldn’t support a member of the LDS Church. The latter data point is of course more relevant, since Harry Reid is not mounting a primary challenge to President Obama — but should Romney and Huntsman be worried?
Mormons are only more popular than gays and atheists:
At 22%, Americans’ resistance to electing a Mormon president, even one nominated by their own party, is exceeded only by their opposition to electing someone who is either gay or lesbian (32%) or an atheist (49%). By contrast, less than half as many, 10%, say they would not vote for a Hispanic, and fewer than 10% would not vote for a nominee who is Jewish, Baptist, Catholic, female, or black.
Data related to the the oft-cited Kennedy election suggests that a Mormon candidate might be able to gain some ground before November 2012, but not much. It also might be relevant that Mormons only make up 2-3% of the U.S. population, compared to Catholics at over 23% in 1960 , the last time Catholics acted as a swing vote:
Still, it is significant that in 1959, the year before John F. Kennedy won election as the nation’s first Catholic president, 25% of Americans — including 22% of Democrats, 33% of Republicans, and 18% of independents — said they would not vote for a Catholic. Public opposition fell to 21% by May 1960 and to 13% by August 1961.
Finally, some more interesting slicing of the data by Gallup, which suggests that educational attainment decreases bias against Mormon and other minority candidates:
The largest differences in opposition to voting for a Mormon for president are by educational level, with adults who have not attended college more resistant than those with some college experience or college graduates. This educational pattern is seen in attitudes about voting for someone from almost all of the specific religious or demographic groups tested in the poll.
There are no significant differences on this question by gender, age, region of the country, or religious preference. Additionally, the views of Americans who attend their place of worship weekly are no different from those of less frequent attenders or non-attenders.