Religion hasn't been an issue in American presidential politics since 1960. That may change in 2008 if Massachusetts Gov. Mitt Romney remains a leading candidate for the Republican nomination.

More than a third of registered voters — 35 percent — say they wouldn't vote for a member of The Church of Jesus Christ of Latter-day Saints for president, the latest Bloomberg/Los Angeles Times poll finds. That's considerably more than say they wouldn't vote for a Catholic, Jew or evangelical Christian. Only a Muslim gets a higher negative response.

Among all respondents, 37 percent say they wouldn't vote for a Mormon. More than two in five Democrats say they wouldn't do so, while about a third of both Republicans and independents say they wouldn't. Females are slightly more negative toward a Mormon candidate than males.

"It's a sign that this is going to be a factor in Romney's campaign," said Scott Rasmussen, an independent pollster and president of Rasmussen Research in Ocean Grove, N.J.

By comparison, 22 percent of registered voters say they wouldn't support an evangelical Christian, 14 percent wouldn't back a Jewish candidate, and 9 percent say no to a Catholic. Fifty-three percent say they wouldn't vote for a Muslim.

The anti-Mormon rating "is a concern, but you have to remember this is all hypothetical now without even mentioning a candidate," said Susan Pinkus, the Los Angeles Times' polling director. "It all hinges on who the candidate is and how the public perceives him."

In an interview on Friday, U.S. Health and Human Services Secretary Michael Leavitt said the religion issue will fade over time.

"I think it will be a curiosity to people," said Leavitt, a former Utah governor who is also a Mormon.

"There will be a lot of folks who will say, 'I am worried a lot of people will worry about that.' I don't. In time, people's curiosity will be satisfied and it will ultimately not be a factor."

Julie Teer, a Romney spokeswoman, said Romney typically doesn't comment on polls.

The Bloomberg/Los Angeles Times poll surveyed 1,321 adults nationwide, including 1,170 registered voters, from June 24 through June 27. The poll has a sampling margin of error of plus or minus three percentage points.

Romney, 59, grew up in the LDS Church and led a group of Boston-area congregations for eight years before running for governor. In a March interview with Bloomberg News, he said he faces frequent questions about his religion but that people of different faiths identify with the core values of Mormonism, including a strong family, honesty and respect for human life.

The last time religion was a factor in a presidential election was when John F. Kennedy, a Catholic, ran in 1960. Kennedy captured the presidency after defusing the issue in a Sept. 12, 1960, speech before the Greater Houston Ministerial Association, a Baptist organization.