WASHINGTON — As he begins campaigning for the Republican presidential nomination, Mitt Romney, the former Massachusetts governor, is facing a threshold issue: Will his religion — he is a Mormon — be a big obstacle to winning the White House?

Polls show a substantial number of Americans will not vote for a Mormon for president. The religion is viewed with suspicion by Christian conservatives who make up a vital part of the Republicans' primary base.

Romney's advisers acknowledged that popular misconceptions about Mormonism — as well as questions about whether Mormons are beholden to their church's leaders on public policy — could give his opponents ammunition in the wide-open fight among Republicans to become the consensus candidate of social conservatives.

Romney, in an extended interview on the subject as he drove through South Carolina last week, expressed confidence that he could quell concerns about his faith, pointing to his own experience winning in Massachusetts. He said he shared with many Americans the bafflement over such obsolete Mormon practices as polygamy — he described it as "bizarre" — and disputed the argument that his faith would require him to be loyal to his church before his country.

"People have interest early on in your religion and any similar element of your background," he said. "But as soon as they begin to watch you on TV and see the debates and hear you talking about issues, they are overwhelmingly concerned with your vision of the future and the leadership skills that you can bring to bear."

Still, Romney is taking no chances. He has set up a meeting later this month in Florida with 100 ministers and religious broadcasters. That gathering follows what was by all accounts a successful meeting at his home last fall with evangelical leaders, including Jerry Falwell; Franklin Graham, who is a son of the Rev. Billy Graham; and Paula White, a popular preacher.

Romney said he is giving strong consideration to a public address about his faith and political views, modeled after the one John F. Kennedy gave in 1960 in the face of a wave of concern about his Catholicism.

Romney's aides said he has closely studied Kennedy's speech in trying to measure how to navigate the task of becoming the nation's first Mormon president, and he has consulted other Mormon elected leaders, including Sen. Orrin G. Hatch, R-Utah, about how to proceed.

Romney appears to be making some headway. Several prominent evangelical leaders said that, after meeting him, they had grown sufficiently comfortable with the notion of Romney as president to overcome any concerns they might have about his religion.

On a pragmatic level, some said that Romney — despite questions among conservatives about his shifting views on abortion and gay rights — struck them as the Republican candidate best able to win and carry their social conservative agenda to the White House.