The four remaining candidates sparred about the hot issues

Sparks flew last night as the four remaining GOP candidates came together in a final, boisterous debate two days before South Carolina's primary — but Newt Gingrich's love life may have stolen the show.

CNN correspondent John King was angrily rebuked by Gingrich after he opened the evening by asking about the “open marriage” Gingrich had sought with his second wife, Marianne.

"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 over sustained cheering and whooping from the audience.

It was the first chance Gingrich had to respond to an ABC News interview that had previously aired, in which Marianne revealed that Gingrich had asked her for an "open marriage" rather than a divorce so he could continue cavorting with his mistress, Callista Biseck, to whom he is now married.

Finally, Gingrich got around to answering the question. "Let me be quite clear," he said. "The story is false."

The evening was otherwise filled with familiar topics of debate as the candidates took their last opportunities to distinguish themselves before the nation's third Republican primary vote on January 21.

Rick Santorum attempted to present himself as a more conservative option and a candidate who could effectively contrast with President Barack Obama in the fall. Gingrich, who previously called on Santorum and now-former candidate Rick Perry to drop out of the race and support him, continued to question if Santorum had the experience for a large undertaking such as a presidential campaign. "Grandiosity has never been a problem with Newt Gingrich," Santorum replied. Santorum took Mitt Romney and Gingrich to task for their stances on healthcare, claiming they've been playing "footsies with the left."

Romney was once again pressed on the matter of his tax returns. Responding to questions earlier in the week, Romney said he may publicly release them sometime around April and revealed that he probably pays a 15 percent tax rate — a rate lower than many working Americans pay.

Romney is estimated to be worth between $190 million and $250 million, and he acknowledged that he anticipates attacks from Democrats about his personal wealth. "I know the Democrats want to go after the fact that I've been successful," he said. "I'm not going to apologize for being successful."

The Twitterverse was buzzing with talk of the debate, particularly on the recent allegations regarding Gingrich's personal life. Here are a few highlights:

"Newt Gingrich's ex-wife claims he wanted an open marriage. How sad is this world that two women have to fight over Newt Gingrich?"

—Julius Sharpe @juliussharpe

"Newt yells at John King, calls him "close to despicable." True. King is standing very close to Gingrich."

—Paul Begala @PaulBegala

"Fewer candidates in the debate means having to listen to more from each of the four remaining morons. Less Perry means more Mitt. Ugh."

—Dan Savage @fakedansavage

”Lots of folks calling #CNNDebate 'entertaining.' Shldn't it have been informative? If I wanted entertainment, I'd watch a sitcom."

—rfbarnes @rfbarnes

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