Gingrich faces ex-wife allegations; interview on 'Nightline' at 11:30 tonight

BEAUFORT, S.C. (AP) — In an up-and-down kind of campaign day, Republican presidential candidate Newt Gingrich picked up an endorsement today from former rival Rick Perry but also faced new accusations from one of his former wives that he had asked her permission to have an "open marriage" after she learned he was having an affair.

The former House speaker also prepared to release his 2010 income tax returns, certain to bring fresh scrutiny to his campaign.

Two days before the pivotal South Carolina primary, Gingrich's political and private life were clashing just as new polls showed him rising as he looks to overtake GOP front-runner Mitt Romney in the third state to weigh in on the presidential race. Gingrich has seen his crowds grow in recent days after a strong performance in a debate Monday.

With the second debate of the week looming Thursday night, it was unclear how the new revelations from Marianne Gingrich of Leetonia in Columbiana County would play in a state where religious and socially conservative voters hold sway.

The interview with Marianne Gingrich, her first on television since the divorce from Gingrich in 2000, was set to broadcast tonight on ABC News' "Nightline" at 11:30 p.m.

In excerpts the network released before the broadcast, Marianne Gingrich said that when she learned of Gingrich's affair with Callista Bisek, a congressional staffer, he asked his wife to share him.

"And I just stared at him and he said, `Callista doesn't care what I do,'" Gingrich' second wife said. "He wanted an open marriage and I refused."