Romney, who led Salt Lake's successful 2002 Winter Olympics before serving as governor of Massachusetts, called what Sharpton said an "extraordinarily bigoted kind of statement, and I find it really quite extraordinary."

A spokesman for the LDS Church, Scott Trotter, had little to say about Sharpton's comment. "It's just campaign rhetoric and we're referring everyone back to Romney," Trotter said.

The Catholic League called for Sharpton to "be held accountable for his bigoted outburst" and suggesting it "should finish his career," just as Don Imus' recent racist statements resulted in the cancellation of his radio show. Sharpton was among Imus' harshest critics.

Kiera McCaffrey, the New York City-based league's director of communications, said Mormons are experiencing what Catholics did when John F. Kennedy ran for president in 1960.

Kennedy, who became the nation's first Catholic president, ultimately had to address the question of whether he would be controlled by his church in a speech made just before the election. Romney's faith has raised similar concerns, especially among evangelical Christians.

"Catholics went through it. Now we see members of the LDS Church going through it," McCaffrey told the Deseret Morning News. "We're not hypocrites. If we're going to defend the rights of Catholics to participate in public life, we're going to do the same across the board."

The Rev. Rob Schenck, an evangelical minister who heads the National Clergy Council, issued a statement calling on Sharpton to "immediately apologize to Mr. Romney and the good people of the LDS Church and repent before God for such sinful hubris."

Schenck, who has met privately with Romney to talk about Mormonism, also said that "while many other Christian groups may have differences with LDS doctrine, to question someone else's sincerity of belief in God is the height of pharisaical arrogance."

The reaction to Sharpton's comment will help set boundaries for future discussions of Mormonism and other faiths in the campaign, said Kelly Patterson, director of Brigham Young University's Center for the Study of Elections and Democracy.

"You have evangelical groups and Catholic groups now saying that this is a line that has been crossed," Patterson said. "It helps not just Romney but all other candidates."

Kirk Jowers, director of the University of Utah's Hinckley Institute of Politics, said the controversy "will have no impact on how people perceive the LDS Church or Mitt Romney. ... This is much more about Sharpton."