Alarmed by what they say will be an almost certain decline in the polls, and anticipating a fusillade of negative comments, senior aides and grass-roots supporters to presidential hopeful Mitt Romney are urging the Republican frontrunner to “fight fire with fire” and go on the attack against Jon M. Huntsman Jr. after the former candidate and former governor of Utah sought to undermine Mr. Romney’s already shaky support among conservatives by endorsing his candidacy.

Alarmed by what they say will be an almost certain decline in the polls, and anticipating a fusillade of negative comments, senior aides and grass-roots supporters to presidential hopeful Mitt Romney are urging the Republican frontrunner to “fight fire with fire” and go on the attack against Jon M. Huntsman Jr. after the former candidate and former governor of Utah sought to undermine Mr. Romney’s already shaky support among conservatives by endorsing his candidacy.


“We’re very disappointed that Governor Huntsman has chosen to stoop to this level, at this moment, trying to demonize Governor Romney with these unsubstantiated gestures of encouragement for no other purpose than political gain,” read a statement issued by the Romney campaign. “We call on Mr. Huntsman to repudiate his statements of support for Mr. Romney and to order his staff to repost the many harsh, clever and biting online videos attacking Mr. Romney that they have so shamelessly removed from Mr. Huntsman’s campaign website and a corresponding YouTube channel.”


Romney campaign aides were particularly incensed that “Backflip,” a video highlighting what Mr. Huntsman called Mr. Romney’s flip-flopping on issues like abortion, gun rights and Ohio’s proposal to curb bargaining rights for unions, and another, accusing Mr. Romney of being a “perfectly lubricated weather vane,” had been so hastily taken down.


They said those videos, and numerous others made for the Huntsman campaign, showed voters that there was a clear choice between the two wealthy, white, well-connected, middle-aged, former governors with presidential aspirations who are both Mormons. Now, they say, the Huntsman campaign is seeking to muddy those distinctions purely for political reasons and personal gain.


“For Governor Huntsman to so abruptly change course and try to pretend those attacks never happened is beyond reprehensible,” said one Romney campaign aide.


In a hurriedly drawn press release issued minutes after Mr. Huntsman’s endorsement, the Romney campaign sought to blunt the unforgiving praise. In the release the campaign noted that Mr. Huntsman had hardly sounded enthusiastic about Mr. Romney, devoting only a single sentence — in the middle of a nearly nine-minute-long speech — to the Republican presidential frontrunner. 


The sharply-worded statement “reminded voters” that two weeks ago Governor Huntsman had called Governor Romney “completely out of touch” and said Mr. Romney “was unelectable because he lacks a core.”


The campaign also made it clear that though both men were in Myrtle Beach, S.C., and Mr. Huntsman’s schedule was decidedly free after his address, there were no plans to appear together.


Still, there were concerns in the Romney camp that Mr. Huntsman might yet make good on his promise to record a telephone call emphasizing his support for Mr. Romney and send it out to supporters.


And Mr. Romney’s advisors remain fearful that without a series of robust attack ads to counteract Mr. Huntsman’s endorsement, the backing of their man by the former Utah governor and former ambassador to China — phone call or not — will quickly seep indelibly into the minds of voters.


New polls taken in South Carolina this week suggest that Mr. Romney has already lost more than half his support since Mr. Huntsman on Monday called on the Republican Party to coalesce behind the party frontrunner, and Mr. Romney has fallen from the top of the field to a statistical tie with candidates he once was far ahead of, like former Sen. Rick Santorum of Pennsylvania and Gov. Rick Perry of Texas.


“How long can you take the beating before hitting back?” said a senior Romney campaign worker, who added that he was “blown away” by how much damage the Huntsman endorsement had already done. “We don’t want to someday look back and say, ‘Boy, we should have pulled the gloves off.’ ”


Philip Maddocks can be reached at pmaddocks@wickedlocal.com.