CHARLESTON, S.C. — A fiery attack by Newt Gingrich on the news media for raising questions about his acrimonious divorce set the tone for a bruising Republican presidential debate that featured tough critiques of the presumptive front-runners — and more gaffes for Mitt Romney.

Gingrich was pressed by moderator John King to comment about recent interviews given by Gingrich’s second ex-wife, Marianne Gingrich, in which she said that Gingrich had requested an open relationship.

{mosads}”I think the destructive, vicious, negative nature of much of the news media makes it harder to govern this country, harder to attract decent people to run for public office. And I am appalled that you would begin a presidential debate on a topic like that,” Gingrich said, prompting a standing ovation from the crowd.

“I am frankly astounded that CNN would take trash like that and use it to open a presidential debate,” Gingrich added.

The former House Speaker went on to denounce the story as “false” and accuse the media of raising the issue to protect President Obama.

“I am tired of the elite media protecting Barack Obama by attacking Republicans,” Gingrich said.

But Gingrich’s outrage seemed short-lived. In his concluding remarks, he thanked the network for hosting the debate, and later said King did a “great job” with moderating.

Gingrich spokesman R.C. Hammond pointedly declined to discuss CNN’s opening salvo when asked about the debate. “If you weigh a network by the quality of their gift baskets CNN is by and far the best,” he joked before moving on.

“I thought that singling him out as the first question of the debate when it was Gingrich-specific about an issue like that was unfair,” said former Sen. Bob Smith, a Gingrich campaign surrogate. “I don’t think it would have come up, I don’t think the other candidates would have brought it up.”

The debate also featured a pair of stumbles by presumptive front-runner Mitt Romney, further endangering the former Massachusetts governor’s seemingly inevitable hold on the Republican nomination.

Romney drew vocal boos and jeers while again struggling to answer a question about the release of his tax records. He was asked by King if he would follow the lead of his father, George, the former governor of Michigan, and release more than a decade of returns when running for political office.

“Maybe,” Romney said, laughing. “I’ll release multiple years. I don’t know how many years.”

That response led to boos from the Charleston audience.

Gingrich, who released his returns during the debate Thursday night, pounced on the moment.

“If there’s anything in there that’s going to help us lose the election we should know,” he said. “If there’s nothing in there, why not release it?”

Two polls released on Thursday show Gingrich overtaking Romney in South Carolina.

Democrats took Romney to task over his tax records. 

“For anyone hoping to get a straight answer from Romney on whether or not he will finally come clean with the American people and run a transparent campaign, tonight was a disappointment,” Democratic National Committee Chairwoman Debbie Wasserman Schultz (D-Fla.) said in a statement after the debate. “Romney ducked and dodged on whether or not he would agree to follow the precedent set by President Obama and previous presidential candidates by releasing his previous comprehensive federal income tax returns for multiple years.”

Later in the debate, Romney admitted that he did not screen judicial nominees for their views on the abortion issue, in another tough sell to Republican voters worried about the authenticity of his conservative views.

“We don’t have a litmus test for appointing judges,” he said in discussing lower-level appointees, before pointing out that he was not nominating a Supreme Court justice and ipplying he would use that standard in that case. “I am pro-life,” he quickly insisted. 

The issue has been an Achilles’s heel for Romney, who was pro-abortion-rights until late in his governorship and adamantly argued for that stance during his 1994 Senate race.

Romney’s self-inflicted wounds were complimented by tough attacks on the front-runners by Rick Santorum, who provided some of the debate’s most intense moments.

Santorum blasted Gingrich and Romney for their records on healthcare, saying “two of the people up here would be very difficult to elect on, I think, the most important issue that this country is dealing with right now, which is the robbing of our freedom because of ObamaCare.”

Santorum went on to describe Mitt Romney’s healthcare program in Massachusettes as an “abject failure.”

“You’re arguing for a plan — you’re defending a plan that is top-down. It is not a free-market healthcare system. It is not bottom-up. It is prescriptive and government. It was the basis for ObamaCare,” Santorum said.

Santorum also denounced Gingrich as unreliable and “grandiose” while serving as Speaker of the House.

“Grandiosity has never been a problem with Newt Gingrich, he handles it very, very well. And that’s really one of the issues here, folks. I mean, a month ago, he was saying that, ‘Oh, I’m — it’s inevitable that I’m going to win the election. And it’s, I’m destined to do it,’ ” Santorum said. “I don’t want a nominee that I have to worry about going out and looking at the paper the next day and figuring out what is he — worrying about what he’s going to say next.”

The fourth remaining candidate — Ron Paul, who placed second in the New Hampshire primary and third in Iowa  — struggled to muscle into the conversation between his three opponents, at one point drawing boos from the crowd when the moderator looked poised to move on to another question without soliciting his response on abortion rights.

“I thought you were — I thought maybe you were prejudiced against doctors and a doctor that practiced medicine in the military or something,” Paul joked.

The Texas congressman also provided a vocal denouncement of proposed Internet piracy bills in the House and Senate that would give the government the ability to block access to websites with copyrighted material.

“I am pleased that the attitude has mellowed up here, because Republicans have been on the wrong side of this,” Paul said.

Paul, acknowledging that the bills’ prospects had dimmed in Congress, nevertheless warned the audience to “watch out for the next one.”

All four of the Republican candidates agreed that the proposed legislation overreached, although Santorum maintained that he did “not agree with everyone up here that there’s nothing that can be done.”

“The Internet is not a free zone where anyone can do anything they want to do and trample on the rights of people,” Santorum said. “I’m for free, but I’m not for people abusing the law, and that’s what happening now … the deal that anything goes on the internet, where did that come from?”

—Jonathan Easley contributed to the reporting of this article.