Obviously, Obama's victory in 2008 did not put racial issues to rest. "He is never on stable ground, racially," Wadsworth observed.
Romney has tried to push past anti-Mormonism, with mixed success. His membership in the Church of Jesus Christ of Latter-day Saints has been an issue his entire political career.
In 2007, during his presidential primary battle against Arizona Sen. John McCain, he gave a speech to quiet concerns about his faith. "I do not define my candidacy by my religion. A person should not be elected because of his faith nor should he be rejected because of his faith," Romney said in the address, which used the word "Mormon" only once.
There continue to be blatant expressions of hostility toward Mormons. For example, there is an "I Hate Mormons" page on Facebook.
But J.B. Haws, a historian at Brigham Young University who researches public perception of the Mormon church, said most common suspicions about Mormons were rehashed in the 2008 election and this year's GOP primary, so moving forward the discussion is likely to be more substantive and informed.
"But that doesn't change the fact that the questions will still be tough and pointed," Haws said.
The Mormon church was founded in 1830 by Joseph Smith, who said God directed him to restore the true Christian church by revising parts of the Bible and adding the Book of Mormon as a sacred text. Smith said an angel directed him to a buried holy book in upstate New York, written on golden plates, which he translated from "reformed Egyptian" into the Book of Mormon. Theological differences have led many Christians to conclude that Mormons are not part of historic Christianity.
There's the issue of polygamy, though the Mormon church renounced the practice in 1890.
Montana Gov. Brian Schweitzer, a Democrat, recently took the opportunity of a Daily Beast interview to say that Romney's father, George, was "born into (a) polygamy commune in Mexico." (Mitt Romney's grandfather, Gaskell, had one wife, but his great-grandfather, Miles Park Romney, had four and fled to Mexico in 1885 to escape U.S. anti-polygamy laws.)
One of the toughest questions probably will focus on the Mormons' former ban on men of African descent in the priesthood. When the church lifted the prohibition in 1978, leaders didn't explain the theology behind it. That left questions about church doctrine on race, even though Mormon leaders repeatedly denounce racism.
It's an issue that Mormons discuss among themselves. But when it's brought up in a campaign setting, many Mormons say it's just an attempt to embarrass Romney.
Several conservatives have recently predicted that liberals, rankled by Mormon opposition to gay marriage and emphasis on stay-at-home motherhood, would use religion to "smear" Romney. "It's way out of bounds, but that's what's going to happen," said a prominent Mormon, Sen. Orrin Hatch, R-Utah.
But liberals are not the only ones who are suspicious of the Mormons. Vice President Joe Biden told Esquire magazine that faith shouldn't be a factor in elections, so "that's why I'm so angry about the way they're treating Romney." By "they," Biden probably was focusing on evangelicals, who make up a big part of the GOP base.
When Liberty University, the school founded by the late Rev. Jerry Falwell, announced Romney as commencement speaker on May 12, hundreds of angry comments were posted on Liberty's Facebook page by people who said they were students or alumni, objecting to giving a Mormon a platform. The school responded by affirming its welcome to Romney.
But evangelicals are among the country's most politically conservative voters, and "they're going to hold their nose and vote for Romney. They're certainly not going to join the Obama campaign," said Patrick Mason, author of "The Mormon Menace: Violence and Anti-Mormonism in the Postbellum South."
Anderson, the pollster, said his research has found that evangelicals know more than other groups about what Mormons actually believe, and despite their religious differences tend to view Mormon values as positive.