COLLEGE STATION, Tex., Dec. 6 — Mitt Romney asked the nation on Thursday not to reject his presidential candidacy because of his religion, assuring evangelical Christians and other religious voters that his values matched theirs in a speech that used the word “Mormon” only once.
The passing mention of his Mormonism in his 20-minute speech here at the George Bush Presidential Library underscored just how touchy the issue of Mr. Romney’s faith has been since he began running for the Republican nomination. He and his aides agonized for months over whether to even give the speech, with those who argued against it saying there was no need to do it because he was doing so well in early voting states, advisers said.
But the political dynamic has changed, with Mr. Romney’s onetime dominance of the Republican field in Iowa faltering as evangelical voters have been drawn to Mike Huckabee, a former Baptist pastor, in these final weeks before the state’s crucial caucuses.
Evangelical Christians, who make up a crucial voting block in the Republican Party, consider Mormonism to be heretical, and polls have indicated a significant number of Americans are less likely to vote for a Mormon presidential candidate.
Nevertheless, Mr. Romney said he would not distance himself from what he called “the faith of my fathers.”
“I believe in my Mormon faith and endeavor to live by it,” he said.
But showing the fine line he was treading, he promised not to be beholden to church authorities, and devoted the majority of his address to calling for a robust role for religion in public life, declaring there was a common moral heritage across religious lines in the country that he would champion.
“I will take care to separate the affairs of government from any religion, but I will not separate us from the God who gave us liberty,” he said, drawing applause from an audience of about 300 invited guests, which included supporters and religious leaders. “Nor would I separate us from our religious heritage.”
While Mr. Romney appeared to be directing his message especially to evangelical voters, the reaction among their leaders was mixed.
Steve Carlson, a board member of the Iowa Christian Alliance and a member of a Pentecostal church in Sioux City, said there was little Mr. Romney could have said today to allay his concerns about Mormon theology and his candidacy.
Mr. Carlson said he had been leaning toward Mr. Huckabee or Fred D. Thompson in large part because of problems he has with Mormonism. The speech, he said, did nothing to change that.
“He didn’t sway me one way or the other,” he said. “I don’t know anything he could have said.”
But Oran P. Smith, president of the Palmetto Family Council, a Christian conservative group in South Carolina, who watched the speech with some of his staff, said he thought Mr. Romney’s address would help him.
“He turned it into a very red-meat conservative speech,” Mr. Smith said.
Mr. Romney’s speech was throughout a delicate balancing act in which he asserted that specific religious doctrines should not matter in the voting booth but argued that the nation’s founders envisioned a prominent place for faith in the public square. That contention was challenged after the speech by advocates for the separation between church and state.
The speech was peppered with declarations appealing to Christian conservatives about the importance of religious expression, whether in the civil rights movement, or the anti-abortion cause, although he failed to mention that he had supported abortion rights until relatively recently.
“In recent years, the notion of the separation of church and state has been taken by some well beyond its original meaning,” he said. “They seek to remove from the public domain any acknowledgment of God. Religion is seen as merely a private affair with no place in public life. It is as if they are intent on establishing a new religion in America — the religion of secularism. They are wrong.”
Mr. Romney made clear he would not back away from his personal spiritual beliefs.
“Some believe such a confession of my faith will sink my candidacy,” he said. “If they are right, so be it. But I think they underestimate the American people. Americans do not respect believers of convenience. Americans tire of those who would jettison their beliefs, even to gain the world.”
But Mr. Romney said it was inappropriate for a presidential candidate to be asked to explain the details of his religion.
“To do so would enable the very religious test the founders prohibited in the Constitution,” he said. “No candidate should become the spokesman for his faith. For if he becomes president he will need the prayers of the people of all faiths.”
He said later: “We do not insist on a single strain of religion—rather, we welcome our nation’s symphony of faith.”
Mr. Romney pointed to his public record, his governorship of Massachusetts, as proof of his independence from his church.
“I will serve no one religion, no one group, no one cause, and no one interest,” he said. “A president must serve only the common cause of the people of the United States.”
His lone allusion to concerns about Mormonism as a departure from Christian orthodoxy came when he talked about his belief that “Jesus Christ is the Son of God and the Savior of mankind.”
In a notable difference from the way he has talked about this on the stump, he added a caveat: “My church’s beliefs about Christ may not all be the same as those of other faiths.”
The couching appeared to be a reaction to how some evangelicals have recoiled from Mr. Romney’s past efforts to signal kinship with them. They say their understanding of Jesus Christ is markedly different from that of Mormons.
Advisers to Mr. Romney said their goal was not necessarily to reach evangelicals but all Americans, pointing out this was a rare opportunity during a primary to have all eyes on their candidate in something of a presidential moment.
With about 100 members of the press, from as far away from Japan, registering for the event, Mr. Romney was introduced by former President George Bush, an old friend who has not endorsed anyone yet.
Afterward, Mr. Romney’s advisers said privately that they hoped the speech would help him with his other, arguably larger, obstacle: lingering questions about the firmness of his convictions given his shifting positions and tone on issues like abortion, gay rights and gun control over the years.
When John F. Kennedy addressed the issue of his Roman Catholic religion in a similar speech when he was running for president in 1960, he took hostile questions hurled at him by ministers. Mr. Romney’s was a friendly crowd that included, in the front row, four of his five sons and his wife, Ann, as well as many affiliated with the campaign.
And Kennedy and Mr. Romney were reaching for different goals. Kennedy was trying to convince the ministers that his faith would not dictate his governance, while Mr. Romney was highlighting how the values he derived from his faith — and shared with religious conservatives — would inform his leadership.
To that end, he recalled the early days of the First Continental Congress in Philadelphia in the fall of 1774, when Boston was occupied by British troops and war loomed.
Someone suggested the members pray, he said, but some there voiced objections, because there were too many divisions among various churches.
“Then Sam Adams rose, and said he would hear a prayer from anyone of piety and good character, as long as they were a patriot,” Mr. Romney said. “And so together they prayed, and, together, they fought, and together, by the grace of God, they founded this great nation.”