BOSTON -- Former Massachusetts governor and Republican presidential candidate Mitt Romney addressed the issue of his Mormon faith in a speech at the Bush presidential library in Texas Thursday, saying he refuses to distance himself from it, but at the same time reassuring voters he won't allow the Church of Jesus Christ of Latter-day Saints to govern his decisions as a political leader.

"I will put no doctrine of any church above the plain duties of the office and the sovereign authority of the law," Romney said in a prepared speech given at the College Station library. The address was an effort to address concerns of voters who have doubts about electing a Mormon president.

"There are some for whom these commitments are not enough. They would prefer it if I would simply distance myself from my religion, say that it is more a tradition than my personal conviction, or disavow one or another of its precepts," Romney said. "That I will not do. I believe in my Mormon faith and I endeavor to live by it. My faith is the faith of my fathers -- I will be true to them and to my beliefs."

Romney said he believes voters will have tolerance and respect for his loyalty to his faith and he referenced a similar 1960 speech given by John F. Kennedy, the first Catholic elected president.

"Some believe that such a confession of my faith will sink my candidacy. 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."

The candidate's speech is seen by some as a response to the concerns of conservative Christian groups that have often been stalwart supporters of Republican candidates. Political analysts say those groups have helped boost the prospects of Romney rival Mike Huckabee, a former Baptist minister, in Iowa. The state will hold caucuses next month that kick off the official presidential campaign season.

"I do not define my candidacy by my religion. A person should not be elected because of his faith, nor should he be rejected because of his faith," Romney said

Romney went on to say he is often asked about the tenets of his faith and he tells people Mormons believe "that Jesus Christ is the Son of God and the Savior of mankind," with their own "unique doctrines and history."

He said the differences in his church's doctrines should not be "bases for criticism but rather a test of our tolerance. Religious tolerance would be a shallow principle indeed if it were reserved only for faiths with which we agree."

The candidate, who is near the top of the polls in both Iowa and New Hampshire, said although some people want him to describe and explain his church's distinctive doctrines, he doesn't think that's appropriate.

"To do so would enable the very religious test the founders prohibited in the Constitution," Romney said.

Romney went on to say that the nation's founding fathers proscribed a state religion so that no religion could dictate government actions and no government could restrict the free practice of any religion. He denouced, however, what he called a move toward creating a religion of "secularism" in the country, which he rejects.

"The founders proscribed the establishment of a state religion, but they did not countenance the elimination of religion from the public square. We are a nation 'Under God' and in God, we do indeed trust," he said.

"We should acknowledge the Creator as did the Founders -- in ceremony and word. He should remain on our currency, in our pledge, in the teaching of our history, and during the holiday season, nativity scenes and menorahs should be welcome in our public places," Romney said.

"Our greatness would not long endure without judges who respect the foundation of faith upon which our constitution rests. 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," Romney said.

"I don't think his Mormonism is a deal breaker for most Americans, but only Mitt Romney can close the deal," Richard Land, president of the Southern Baptist Convention's Ethics & Religious Liberty Commission, told ABC's "Good Morning America." Asked directly if he thought Mormons were Christians, Land said, "No, I do not."

In an AP-Yahoo poll last month, half said they had some problems supporting a Mormon presidential candidate, including one-fifth who said it would make them very uncomfortable.

Fifty-six percent of white evangelical Christians -- a major portion of likely participants in the early GOP presidential contests in Iowa and South Carolina - expressed reservations about a Mormon candidate. Among non-evangelicals, 48 percent said it troubled them. Almost a quarter -- 23 percent -- of evangelicals said they were very uncomfortable with the idea.