CHARLESTON, S.C. (AP) - Newt Gingrich's Republican rivals are not eager to criticize him on his marital woes.

Gingrich's ex-wife says in an interview with ABC News that the former House speaker asked her for an open marriage.

In a nationally televised debate Thursday night, Mitt Romney, Rick Santorum and Ron Paul were asked whether Gingrich's past infidelity is relevant to the campaign.

Romney says it's time to get on to the real issues.

Santorum says the U.S. is a forgiving country and that no one is perfect. He adds that it's up to voters in South Carolina to decide if the matter is relevant.

Paul says the attacks on Gingrich are being generated by the media. But he adds that he's proud his wife of 54 years is with him.

While rivals declined to criticize Gingrich, he criticized CNN host John King for asking about the marriage issue, CBS News reports.