CHARLESTON, South Carolina (Reuters) - Republican presidential candidates tore into each other on Thursday and Newt Gingrich snarled at the CNN moderator in a raucous debate two days before the South Carolina primary, which may decide the nomination race.
The two-hour prize fight came at the end of one of the campaign's most tumultuous days, with Texas Governor Rick Perry dropping out and a new winner emerging in the Iowa caucuses held more than two weeks ago.
Tension has increased as polls show the race tightening between front-runner Mitt Romney and Gingrich, who took offense at a question about a previous marriage from CNN moderator John King and lashed out.
"I think the disruptive, vicious, negative nature of the news media makes it harder to govern this country," Gingrich fumed. "I am appalled that you would begin a presidential debate on a topic like that."
King had asked the former House of Representatives speaker about ex-wife Marianne Gingrich, who told ABC News Gingrich had sought an "open marriage" when he was having an affair in the 1990s. Gingrich denied the allegation.
Gingrich stands a growing chance of defeating former Massachusetts governor Romney in South Carolina and puncturing his drive to win the Republican presidential nomination to face Democratic President Barack Obama in November.
A new Reuters/Ipsos poll showed the South Carolina race getting closer with Romney at 35 percent support, Gingrich with 23 percent and former Pennsylvania senator Rick Santorum with 15 percent.
Romney was again dogged by questions about his tax payments after spending days on the campaign trail fending off criticism for paying taxes at a low 15 percent rate.
Asked whether he would release tax returns covering many years, Romney answered: "Maybe." That drew boos from the audience in the picturesque coastal city of Charleston.
Eager to upset the front-runner, Gingrich's team released their candidate's most recent tax returns half an hour into the debate, a reminder that multi-millionaire Romney still had not produced his own.
Romney will take a huge step toward claiming the Republican nomination if he wins on Saturday after his New Hampshire win on January 10 and his near-victory in Iowa on January 3.
But he is suddenly looking beatable in South Carolina, under pressure on taxes, attacked over his record as a private equity executive and struggling to convince rock-ribbed Republicans here he is a true conservative.
Perry quit the presidential campaign on Thursday and endorsed Gingrich, while Romney lost his place as winner of the Iowa caucuses when the Republican Party announced Santorum had actually won more votes.
Santorum is anxious to make a breakthrough in South Carolina to revive his fading hopes.
Gingrich took the brunt of Santorum's fire in the debate.
He gave a blistering critique of Gingrich's tenure as House speaker, calling him "grandiose" and suggesting he has behaved erratically. "I don't want a nominee that I have to worry about going out and looking at the paper the next day and ... worrying about what he's going to say next," Santorum said.
Gingrich insisted he led a Republican revolution and worked with Republican President Ronald Reagan.
"I participated in the '80s in an enormous project of economic growth and, with President Reagan's leadership, the American people created 16 million jobs," he said.
But Romney quibbled with how much Reagan actually appreciated Gingrich, pointing out that Reagan mentioned Gingrich only once in his presidential memoir.
"I mean, he mentions George Bush 100 times. He even mentions my dad once," Romney said.
Romney came into the debate under strong pressure to turn back Gingrich.
He faced questions again about his experience at Bain Capital, which bought companies and restructured them, sometimes resulting in job losses. The issue has hurt him in South Carolina, where unemployment remains around 10 percent. Gingrich lobs frequent attacks at him on this.
Romney pledged to release his own taxes in April and defended his wealth. "I'm not going to apologize for being successful," he said.