by Olivier Knox

CONCORD - Mitt Romney's rivals for the Republican presidential nomination on Sunday slammed his "pious baloney" on the campaign trail and tarred him as a timid moderate sure to lose to Barack Obama.

Squaring off in their second televised debate in just 10 hours, the other contenders seemed determined to seize what could be a final chance to dull Romney's momentum days before New Hampshire's bellwether primary on Tuesday.

Former House speaker Newt Gingrich accused the former Massachusetts governor of being a "moderate" with "an economic plan so timid it resembles Obama's" and warned Republicans against thinking Romney is the most electable candidate.

"I do think the bigger the contrast, the bolder ideas, the clearer the choice, the harder it is for that billion-dollar campaign to smear his way back into office" in the November 6 elections, said Gingrich.

"I'm very proud of the conservative record I have," replied Romney, who is seen as the likely nominee if he can make good on his vast lead in opinion polls here and in South Carolina after eking out a win in the Iowa caucuses last week.

In a shot at Gingrich and former senator Rick Santorum, a devout Christian conservative, Romney said "someone who isn't a lifelong politician" would have a better shot at beating Obama and underlined "we've got to nominate a leader."

Santorum pointed to Romney's decision not to run for reelection as governor in the face of poor poll numbers and thundered: "We want someone, when the time gets tough -- and it will in this election -- we want someone who's going to stand up and fight for the conservative principles, not bail out and not run."

"Politics is not a career. For me, my career was being in business," said Romney, who made millions as a venture capitalist and mounted a failed bid for the party's nomination in 2008.

"Can we drop a bit of the pious baloney?" Gingrich scolded in an exasperated tone. "You were running for president while you were governor... you've been running consistently for years and years and years."

While the attacks amounted to a sharp escalation in tone against Romney, he gave as good as he got and committed no major errors, making it unlikely that the assault would derail his better-funded, better-organized campaign.

Still, the debates could shape Tuesday's vote, which may drive one or more candidates from the race, resetting a field that has been led alternately by Romney and successive conservatives who have surged and fallen back.

Romney's vast campaign war chest and high-profile endorsements have fed his image as the candidate to beat, but he faces stubborn doubts about his conservative credentials and has never been able to push his support from Republicans nationwide above 30 percent.

And a New Hampshire tracking poll from Suffolk University in nearby Boston could breath fresh life into his rivals: It found his standing in his state slipping for the fourth straight day, though still enjoying a wide lead.

The survey gave Romney 35 percent support, down from 43 percent last Tuesday, well above Paul's second-place 20 percent, while former US envoy to China Jon Huntsman gained to 11 percent, and Gingrich sits at nine percent.

The poll found Santorum has fallen to eight percent -- a slide pollsters have blamed on his virulent criticisms of gay rights in independent-minded New Hampshire -- while Perry was at one percent.

The former senator -- who has likened being gay to bestiality -- stuck by his fierce opposition to gay marriage and gay adoptions but struck a far softer personal tone when asked what he would do if he had a son tell him he was gay.

"I would love him as much as I did the second before he said it. And I would try to do everything I can to be as good a father to him as possible," said Santorum.

Romney said he -- like Obama -- opposes same-sex marriage but warned that voters seeking a candidate who would deny gays "full rights in this country" that "they won't find that in me."

Polls have shown the US public increasingly supportive of gay rights -- especially among the young.

Huntsman scored one of the biggest applause-getting lines of the debate when he rebuked Romney for attacking his service as Obama's first ambassador to China, saying he was "putting my country first."

Romney retaliated, saying "the person who should represent our party running against President Obama is not someone who called him a remarkable leader and went to be his ambassador in China."

But Huntsman won more applause when he shot back to NBC moderator David Gregory: "This nation is divided, David, because of attitudes like that. The American people are tired of the partisan division. They have had enough."