Other rivals disagreed.
On his campaign bus Thursday night, Sen. John McCain, R-Ariz., suggested Huckabee's recent success in Iowa led Romney to make the speech.
"He [Huckabee] knows there's a strong voting bloc in Iowa that call themselves 'Christian conservatives,'" McCain said. "He's always been trying to appeal to them. I saw some of his mailers, stuff out there. I think that Huckabee's rise in the polls has clearly had an impact on a lot of people's strategic thinking."
Not so, Romney told ABC News.
"I have been through a couple of surges now. First was the McCain surge, then the Giuliani surge, and then the Fred Thompson surge, and now it's the Mike Huckabee surge. And in the past, what's happened is, when the surge occurs, people look more closely at the record of the vision of the person running … and inevitably the surge kinda deflates. I think you will see the same thing here. I sure hope so."
In his first blog posting for ABCNews.com, ABC News political contributor Matthew Dowd, who served as President Bush's chief strategist in 2004, called the speech "wonderful" but quickly added "[Romney's] fall in the polls has nothing to do with the fact that he is a Mormon, and has more to do with questions of authenticity, and I don't know if one speech can fix that."
Rivals' reactions-- who have turned to God frequently as a topic on the 2008 campaign trail -- weren't quite as harsh.
Rep. Ron Paul, R-Tex., seemingly the libertarian conscience of the Republican Party this election season, defended his GOP rival.
"The recent attacks and insinuations, both direct and subtle, that Gov. Romney may be less fit to serve as president of our United States because of his faith fly in the face of everything America stands for. Gov. Romney should be judged fairly, on his record and his character, not on the church he attends," said Paul in a written statement.
Republican candidate and former Sen. Fred Thompson of Tennessee declined to talk about the address during an interview with an Iowa radio station Thursday, saying he would "hate to punt" without hearing the speech for himself, but said he was "Ti-Vo-ing" the speech.
Instead, Thompson talked about his own faith, which he said "has to do with everything I do and everything I hope to be."
ABC News' Christine Byun, Bret Hovell, Matt Stuart and Z. Byron Wolf contributed to this report.