GREER, S.C. — An array of Republicans and conservatives — including some of Mitt Romney’s sharpest critics — rushed to the GOP presidential front-runner’s defense Thursday to counter efforts to paint the former venture capitalist as a job-killer. Under fire, Romney rival Newt Gingrich tempered his attacks on Romney’s tenure at the helm of Bain Capital, but Rick Perry defended his approach.

“We’re disappointed” with the line of criticism, said Thomas Donohue, the head of the U.S. Chamber of Commerce. The business group doesn’t endorse in presidential campaigns, but Donohue said: “We think Romney has had a pretty good track record. Perfect? Hell no, but damn good.”

Former Arkansas Gov. Mike Huckabee, who ran against Romney four years ago, wrote in an online letter: “It’s surprising to see so many Republicans embrace that left-wing argument against capitalism.” And another 2008 foe, former New York mayor Rudy Giuliani, told Fox News Channel: “I’m shocked at what they are doing. I’m going to say it’s ignorant. Dumb. It’s building something we should be fighting — ignorance of the American economic system.”

Romney’s new defenders — many of whom have long histories of disagreeing with the former Massachusetts governor — argued that the attacks on his business record undermined the GOP’s identity and weakened the party’s chief argument against Democratic President Barack Obama, that federal intrusion has stymied the economy’s recovery.

And while the latest comments were more a rejection of attacks on Romney’s record at Bain than an endorsement of Romney as a candidate, they signaled a warming toward Romney by a cross-section of the GOP as his party struggles to settle on a more conservative alternative. They also signaled that attempts by Gingrich, a former House speaker, and Perry, the Texas governor, to cast Romney as a cold-blooded predator in the business world appeared to be backfiring badly — and playing right into the Romney campaign’s hands.

A prominent fundraiser in South Carolina — Barry Wynn — shifted his support from Perry to Romney in light of those attacks, which he said had crossed the line in a political party that values free-market capitalism.

“I’ve been fighting for this cause most of my life,” Wynn said. “It’s like fingernails on the chalkboard. It just kind of irritated you to hear those kind of attacks.”

The controversy over Romney’s Bain tenure began last weekend when Gingrich, seeking a rebound for his candidacy if not revenge for attack ads that crippled his campaign in Iowa, sought to undercut the central rationale of his chief rival’s candidacy — that Romney’s business background made him the strongest Republican to take on Obama.

Perry, whose campaign also is in trouble, joined in.

Both are accusing Romney of being a fat-cat venture capitalist during his days running Bain, laying off workers as he restructured companies and filled his own pockets.

But the criticism of both Gingrich and Perry has been swift, with opponents Rick Santorum and Ron Paul refusing to attack Romney’s time at Bain, and others fearful about bloodying the Republican most likely to become the party’s nominee.

“If you believe what the Obama administration is doing is a direct assault on the private sector and as Republicans we believe that’s the wrong approach, you can’t turn around and say what is going on in the private sector is wrong,” said Jim Dyke, a GOP strategist in South Carolina who is uncommitted to a candidate in the Jan. 21 primary.

The backlash against Gingrich and Perry snowballed Thursday when the U.S. Chamber, one of the nation’s most prominent pro-business lobbying groups, weighed in.

Earlier in the week, conservative radio commentator Rush Limbaugh, often a Romney critic, called Gingrich’s comments “out of bounds for those who value the free market.” Club for Growth President Chris Chocola labeled the attacks “disgusting.” And South Carolina Sen. Jim DeMint, who endorsed Romney in 2008 but is unaligned this year, suggested that Romney critics don’t understand “the principles of our party.”

“To have a few Republicans in this race beginning to talk about how bad it is to fire people…it really gives the Democrats a lot of fodder,” DeMint, arguably South Carolina’s most popular Republican, told conservative radio host Laura Ingraham.

Although presidential contender Jon Huntsman had criticized Romney for a comment he made about firing people, Huntsman said on Wednesday: “If you have creative destruction in capitalism, which has always been part of capitalism, it becomes a little disingenuous to take on Bain Capital.”

Gingrich seems to have gotten the message — to a point.

While Gingrich said “I’m not going to back down” during a campaign stop in Columbia on Thursday, he made no mention of Romney nor did he repeat his criticism of Romney’s record as a venture capitalist.

Instead, Gingrich tried to shift blame, saying that it was his calls to audit the 2008 federal banking bailout that had “rattled a number of so-called conservatives.”

“When you have crony capitalism and politicians taking care of their friends, that’s not free enterprise, that’s back-door socialism,” said Gingrich, who is airing a TV ad describing Romney’s economic plans as timid.

In a television interview later Thursday, Gingrich said he still reserved the right to question Romney’s record “because he’s running for president.”

An outside group supporting Gingrich — called Winning Our Future — pressed ahead with plans to launch an advertising attack on Romney’s time at Bain, complete with a bruising ad and longer-form video in South Carolina assailing Romney as a vicious corporate raider.

Perry, who had likened companies like Bain to vultures, avoided attacking Romney for his role at Bain during two stops in South Carolina on Thursday.

But he defended the approach later, arguing Republicans were better off airing concerns now than letting Democrats exploit it this fall.

“I don’t want to be out there defending practices that put people out of work,” Perry told The Associated Press in Walterboro. “My point is if we’re going to be the party of positive job growth, we need to be really careful about creating these types of situations.”

During a walk between shops in Summerville, S.C., voter Barbara Schimp pulled Perry aside and told him to “lay off” the Bain attack. She told Perry, whom she supports, that he sounds anti-business.

“Roger that,” Perry responded with a wink.

Romney, for his part, has tried in recent days to explain the private equity business. He told reporters in Greer as the day began that in the private sector, some businesses grow and thrive while others have to be cut back in order to survive and become stronger.

“Sometimes you’re successful at that and sometimes you’re not,” Romney said.

Meanwhile, his team was working behind the scenes to blunt the force of the criticism, distributing talking points to surrogates warning against attacking the free-market economy.

On Wednesday night, South Carolina Gov. Nikki Haley, chided Gingrich and Perry indirectly in introducing Romney, whom she has endorsed, during a campaign event in Columbia.

“We have a real problem when we have Republicans talking like dang Democrats against the free market,” Haley said. “We believe in free markets.”