In Iowa, Nye caucused for Romney, the former Massachusetts governor, and turned local curiosity about Mormonism into a teachable moment. He went on a radio talk show to discuss Mormon beliefs and taught a Sunday school class at a Methodist church.

"People just wanted to know a little bit more about what we believed. For them it was 'Why is religion even an issue and what's so different about the Mormons that we should be worried?'" he said.

Persecution is a central part of the Mormon story.

The church was founded in 1830 by Joseph Smith, who claimed that God and Jesus appeared to him in a forest grove and implored him to restore the true church to the world. Smith further said that an angel, Moroni, led him to a set of buried gold plates that when translated from its ancient script became the Book of Mormon.

During the 1800s, Mormons were repeatedly attacked and driven from their homes, making their way west from New York to Ohio and Illinois, where Smith, a candidate for president, was shot and killed in 1844 by a mob while in jail. Mormons again fled, settling in the Utah Territory.

Today the faith claims 13 million members worldwide, more than 5.7 million of them in the United States, where Mormonism is the fourth-largest denomination.

Randy Parker, a 36-year-old Mormon living in American Fork, complained that religion is being used as a test of political fitness for Romney but not for the other candidates. Former Arkansas Gov. Mike Huckabee, a onetime evangelical Baptist minister, has not been asked to explain his faith in the same way, Parker said.

"At what point does a religion attain the status of just being accepted generally?" Parker asked. "I don't know, but Mormonism isn't there. It's kind of opened my eyes, really about the rest of the country."

Similarly, Ken Jennings, the Mormon software engineer from Salt Lake City who won $2.5 million on "Jeopardy!" in 2004 to become the most successful contestant in the game show's history, said: "I guess my feeling is I expected better of America. As a Mormon and an American, I'm feeling a little disillusioned."

Publicly, leaders of the church are dealing with the Romney ride as they do everything — with optimism.

"I think over the long term this is going to be a very, very positive thing for us," said Elder M. Russell Ballard, a member of the Quorum of the Twelve Apostles. Ballard and others have been visiting the editorial boards at newspapers and magazines to discuss Mormonism.

"We're wanting to be a part of the conversation because we do not want people defining us," he said. "Whether we clear up all the misunderstandings is something else, but we certainly had the chance to talk to them about real issues."