Romney and his rivals paraded before about 750 conservative activists, using half-hour chunks of time to rail against abortion rights and gay marriage, and offer tough talk about building a fence along the border with Mexico. All pledged to cut taxes and shrink government.

Romney got polite applause as he vowed to push conservative themes.

"It is essential that we have a Republican president who is pro-life and pro-family," said Romney.

Loudest cheers of the day went to conservative Rep. Tom Tancredo, who railed against illegal immigration. "If you want to call me a single-issue candidate, that's fine as long as you know my issue is the survival of this country," he said.

Meeting with reporters, Romney said the question about his faith was fair.

"I don't know whether I'll give an address on this or not, I may well," said Romney. "A couple of campaigns have raised this issue and that may lead me to give an address at some point."

Other rivals focused on Democrats, mainly Sen. Hillary Clinton.

"If you want to make sure Hillary Clinton is not elected next year, you better voter for Tommy Thompson," said the former Wisconsin Governor.

Some of Romney's critics says he has shifted his views on positions such as abortion and gay rights as he moves from governor to presidential contender.

Romney sought to assure activists of his hard-line views. He said the landmark Supreme Court decision that legalized abortion in 1973 should be overturned and states should be allowed to decide the issue.

He also said he fought an overwhelmingly Democratic Legislature in Boston by pushing for the death sentence during his time in office.

Romney and most of his rivals — minus top tier candidates Rudy Giuliani and John McCain — were appearing at the forum. Joining Romney were Thompson, Mike Huckabee, Sam Brownback, Tancredo and Duncan Hunter.