It's all left some in New Hampshire — where Romney is close to a hometown boy — scratching their heads.
"Is the purpose to destroy Romney? Very often this becomes a double-sided sword," said Phyllis Woods, New Hampshire's Republican national committeewoman, who also worries that Gingrich could be unintentionally helping Democrats.
"I think there is a danger that the negativity expressed by Newt Gingrich could work against him," she said. "But it's certainly not good for the party as a whole. I would hope people would count to 10 and take a deep breath."
There's a long and storied history of candidates in both parties ripping into each other during primary campaigns only to make up afterward.
Hillary Rodham Clinton regularly attacked Obama four years ago, calling him "a hypocrite," among other insults. Clinton, of course, is now the secretary of state in the Obama administration. Sen. John McCain assailed Romney in the hard-fought 2008 campaign but endorsed him this go-round.
And Sam Pimm, Gingrich's New Hampshire field operations director, said he's heard no complaints from residents.
"I think it's about time people heard the truth about Governor Romney's record," he said.
But Gingrich's problem, other New Hampshire Republicans say, stems from his recent promise not to go negative.
"He was supposed to be the nice positive guy and framed himself that way," said Kevin Smith, a GOP candidate for New Hampshire governor. "It's only an issue because he seems to be going back on his word of running a positive campaign."
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