Republican Mitt Romney, vying to become the first Mormon president, said Monday he decided to give a speech focused on his faith and the role of religion in politics because the subject is of interest in early voting Iowa — where he has lost his lead in GOP presidential polls.

"I can tell you I'm not going to be talking so much about my faith as I am talking about the religious heritage of our country and the role in which it played in the founding of the nation and the role which I think religion should generally play today in our society," Romney said in an interview with WBZ-AM.

He added: "I will also talk about how my own values and my own faith will inform my thinking if I were lucky enough to become president of the United States."

The former Massachusetts governor said religion wasn't a factor when his father, former Michigan Gov. George Romney, ran for the White House in 1968.

"But, you know, times have changed and particularly in a state like Iowa, there's been interest in religion generally and I think religion does have a very important role in our society and therefore it's important to talk about our religious heritage," Romney said.

The address, planned for Thursday at the George Bush Presidential Library and Museum in College Station, Texas, will focus on the role of religion in American society.

Romney's staff announced the speech Sunday, after months of debate at his Boston headquarters over whether to make a public address about his religion. They insisted the decision was made by Romney last week, before the latest polls were released.

Nonetheless, the address comes as Romney's bid is threatened in Iowa by underdog Mike Huckabee. The ex-governor of Arkansas and one-time Southern Baptist minister has rallied influential Christian conservatives to erase Romney's monthslong lead and turn the race into a dead-heat.

The speech — titled "Faith in America" — and the Texas site recall the address John F. Kennedy made in Houston as he sought to explain his faith during the 1960 campaign and become the first Catholic president.

From the start of Romney's bid, his Mormon faith has been an issue in the campaign as he tried to position himself as the candidate of the GOP's family values voters. A Pew Research Center poll in September found a quarter of all Republicans — including 36 percent of white evangelical Protestants — said they would be less likely to vote for a Mormon.

Indeed, skepticism about his religion has proven difficult for Romney to overcome, particularly in Iowa, where religious conservatives play a powerful role in GOP caucuses. Romney has invested heavily in the state, hoping to use a win here as a launching pad to the nomination.

Polls show the race a toss up. Just a month ago Romney held a wide lead and Huckabee trailed in the single digits. Huckabee has surged in large part by rallying the GOP's religious right wing.

Last week, Huckabee sought to exploit Romney's weaknesses — his Mormon faith and his reversal on abortion as well as shifts on other issues — by running a TV ad in Iowa that emphasizes his own religious beliefs. The ad doesn't mention Romney but clearly targets him.

"Faith doesn't just influence me. It really defines me. I don't have to wake up every day wondering what do I need to believe," Huckabee says in TV ad. "Let us never sacrifice our principles for anybody's politics. Not now, not ever."

But Huckabee, in an interview on ABC's "This Week," took a pass when asked if Mormonism contradicts the central teachings of Christianity.

Romney, for his part, sought Friday to strengthen his own support among religious and social conservatives, meeting with members of the grassroots network the Iowa Christian Alliance in Dubuque, Iowa.

"I am pro-life. I am pro-family," Romney told them. "If I am the president of the United States — and frankly even if I'm not — I will work hard and tirelessly to preserve marriage as an institution, which is fundamental to the preservation of this great land."

How he should deal with questions about his faith has divided his campaign advisers.

Some advisers had suggested that he give the speech touching on his beliefs and clarifying the impact of his faith on his governmental decision-making. Those advisers privately said that Romney would benefit from such a speech because Mormons pride themselves on the separation of church and state, as well as a tolerance for all religions.

Until now, Romney has chosen an incremental approach supported by other advisers in which he answers questions about his faith during town hall meetings or media interviews. Those advisers' concern was that discussing the tenets of the Church of Jesus Christ of Latter-day Saints would draw too much attention to his religion.