Republican presidential hopefuls tried to blunt frontrunner Mitt Romney's progress but failed to land any telling blows in back-to-back weekend debates ahead of Tuesday's New Hampshire primary.
Squaring off Sunday in their second televised grilling in just 10 hours, Romney's rivals seemed determined not to repeat the relatively light bashing they gave him the previous evening, relentlessly laying into the favorite.
Former House speaker Newt Gingrich, whose ratings have slid in the face of attack ads from Romney's campaign team in recent weeks, said the current leader in the Republican race would lose against incumbent Democrat Barack Obama and at one point accused him of "pious baloney."
Gingrich said the former Massachusetts governor was a "moderate" with "an economic plan so timid it resembles Obama's."
"What Republicans have to ask is, who's most likely in the long run to survive against the kind of billion-dollar campaign the Obama team is going to run?" Gingrich asked, warning voters in the bellwether state of New Hampshire against thinking that Romney is the most electable candidate.
"I do think the bigger the contrast, the bolder the 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 presidential election, said Gingrich.
Romney rebuffed the charge that he was not strong enough to beat Obama.
"I'm very proud of the conservative record I have," said Romney, who is seen as the likely nominee if he can make good on a vast lead in opinion polls here and in South Carolina after squeezing out a win in the Iowa caucuses last week.
And in a shot at Gingrich and ex-senator Rick Santorum, a devout Christian conservative, Romney said "someone who isn't a lifelong politician" would have a better shot at beating Obama.
But Santorum thundered back and painted Romney as weak for deciding not to run for re-election as a governor in the face of poor poll numbers.
"We want someone who's going to stand up and fight for the conservative principles, not bail out," Santorum said.
Romney, who made millions as a venture capitalist and mounted a failed bid for the party's nomination in 2008, retorted that politics "is not a career" for him, but the remark drew an angry response.
"Can we drop a bit of the pious baloney?" Gingrich scolded. "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 committed no major errors, making it unlikely that the assault would derail his better-funded, better-organized campaign.
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.
A vast campaign war chest and high-profile endorsements have fed Romney's image as the man to beat, but he faces stubborn doubts about his conservative credentials and has been unable to push his support from Republicans nationwide above 30 percent.
And a New Hampshire tracking poll from Suffolk University could breathe fresh life into his rivals: It found Romney's standing in the state slipping for the fourth straight day, though he still enjoys a wide lead.
The survey gave Romney 35 percent support, down from 43 percent last Tuesday, well above Ron Paul's second-place 20 percent, while former US envoy to China Jon Huntsman gained to 11 percent, and Gingrich sat at nine percent.
The poll found Santorum had fallen to eight percent -- a slide pollsters have blamed on his virulent criticisms of gay rights in independent-minded New Hampshire -- while Texas Governor Rick 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.
Polls have shown the US public increasingly supportive of gay rights -- especially among the young.
But it was Huntsman who 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."
The former diplomat and Utah governor won further praise from the audience when he told NBC moderator David Gregory: "The American people are tired of the partisan division. They have had enough."
After the New Hampshire primary, Romney's rivals, especially Gingrich, will pour on the attacks in South Carolina, potentially their last shot at loosening his grasp on the nomination.
A group supporting Gingrich reportedly plans to go after Romney's business background this week in a series of ads placed in the southern state.