While President Obama's election as the first African-American to win the White House captured headlines in 2008, Romney's accomplishment this year is more low-key.
If he wins in November, Mitt Romney would be the first president who is a member of the Church of Jesus Christ of Latter-day Saints.
"If you look at it in a historical perspective, it's absolutely incredible," said Richard Lyman Bushman, a Mormon scholar and longtime acquaintance of Romney's, told The Washington Post. "A century-and-a-half ago, Mormons were detested as a people as well as a religion. They were thought to be primitive and crude. And now to have someone overcome all the lingering prejudice, that's a milestone."
But as the primary season yields to the general election season, all things about a candidate become amplified, said political commentator Steven Schier, a political science professor at Carleton College in Minnesota.
"All aspects of a major party's presidential nominee go under a media microscope, but their importance to voters depends very much on how much the opposition campaign draws attention to those traits," Schier said. "In 2008, the McCain campaign refused to make Obama's relationship with the controversial Rev. Jeremiah Wright a campaign issue. In 2012, the Obama campaign has indicated it will not seek to draw much attention to Romney's Mormonism. If that remains the case, Romney's religion will not be a major factor in voters' minds this November.
Nearly 200 years after the founding of Mormonism by Joseph Smith, who ran for president to draw attention to his followers' persecution, Romney's nomination signals how far his faith, and the country's acceptance of it, has come.
The church offered its own low-key response.
"The church's neutrality in political campaigning is well established, and we won't be making any statement today," church spokesman Michael Otterson said.
While Mormonism is one of the world's fastest-growing religions, about one in three Americans say they have an unfavorable view of the Mormon church, a Bloomberg News poll conducted in March indicated.
Uneasiness about a presidential candidate's religion is nothing new in politics. Smith was assassinated after he announced he was seeking the presidency in the 1840s. In the 1960s, John F. Kennedy's presidential bid was met in some quarters by fear that the Vatican would rule the White House because Kennedy was Catholic. In 2008, many people wondered aloud if President Obama, a Christian, was Muslim, even as they took him to task for attending a church where a controversial minister preached incendiary rhetoric.
During his 2008 campaign, the former Massachusetts governor tried to assuage voter fears about his Mormon faith influencing a Romney White House, saying: "If I am fortunate to become your president, I will serve no one religion. A president must serve only the common cause of the people of the United States."
When Romney speaks about religion during the 2012 election cycle, it typically is to portray himself as a man of faith and to draw similarities between his beliefs and those of other Christians, the Post said.
"Central to America's rise to global leadership is our Judeo-Christian tradition, with its vision of the goodness and possibilities of every life," Romney said his May 12 commencement address at Liberty University, an evangelical Christian college. "From the beginning, this nation has trusted in God, not man. … There is no greater force for good in the nation than Christian conscience in action."
For Mormons, however, Romney's presumptive nomination to be the GOP presidential standard-bearer could be a minefield, The Boston Globe reported.
"There's a sense of we're proud to have Mitt Romney doing so well," Quin Monson, a professor at Brigham Young University and a Mormon, told the Globe. "The other side of the coin is there's sort of a sense of trepidation. Or nervousness. Sort of maybe even a fear of the impending maelstrom that I think a lot of Mormons widely believe is coming our way."
Steve Shaw, a political science professor at Northwest Nazarene University and co-author of "The Presidents and Their Faith," said the closest parallel to Mormons and Romney is the way Catholics felt about Kennedy.
"There was this interesting debate: Are we ready for the presidency, and are they ready for us?" Shaw told the Globe.
He noted some prominent Catholics were involved in advocating for Kennedy's campaign, including Boston's Cardinal Richard Cushing and New York's Cardinal Francis Spellman.
Meanwhile, Mormons have played key roles in politics: notably Romney's father, George, ran for president in 1968, Rep. Mo Udall ran in 1976, and Sen. Orrin Hatch ran in 2000. Harry Reid is Senate majority leader.
"It will be good for the church, because many people around the world have really weird ideas of Mormons," former U.S. Sen. Bob Bennett, a Mormon and a Romney supporter, told the Globe. "To have someone who is well educated, successful in his career, successful in his family have this high a profile sends the message to the world: The Mormons are not the crazy cult that many of you think we are."
Romney's religion probably will matter only to specific factions of each major party, Schier said.
"Secular Democrats will view Mormonism with suspicion," he explained. "Strongly religious Republicans will applaud Romney's attachment to his faith. It's clear from polling that conservative evangelicals are not holding Romney's Mormonism against him. They have demonstrated strong support for Romney in recent polls."
The religious right has embraced Romney and will work energetically for his election, Schier said.
"The religious right is upset with Obama's embrace of gay marriage and, in their view, his assault on religious freedom in the new healthcare plan," he said. "That has moved them enthusiastically into Romney's column."