COLUMBIA, S.C. - The future of businessman Herman Cain's troubled campaign for the U.S. presidency appears to rest on discussions he planned with his wife Friday as he makes his first trip home since a woman came forward claiming she had a 13-year extramarital affair with him.

Cain, who has denied the affair and allegations from other women of unwanted sexual advances, planned a Friday afternoon campaign stop in South Carolina before heading home to Atlanta.

The various allegations and questions about his foreign policy knowledge have knocked Cain from the front-runner position he briefly held in the contest to find a challenger to President Barack Obama in 2012.

Newt Gingrich, the former speaker of the House of Representatives, and former Massachusetts Gov. Mitt Romney now lead the race with little more than a month before the first nominating contest, the Iowa caucuses. It is not clear if one of them or another candidate would be the most likely to benefit if Cain were to drop out of the race.

Cain's prospects seem dim if he stays in the race. His standing in the polls is cratering, supporters are wavering and fundraising is limping.

Cain planned a Friday afternoon campaign stop in Rock Hill, South Carolina, before heading home to Atlanta to assess whether the accusation of an affair would be enough to force him from the Republican contest.

"I want to do the assessment that we've got to do. Every time a new bit of information comes up, that stimulates another story in the media and that hurts my family and my wife, and it hurts me," Cain told Fox News Channel on Thursday.

"I'm going to re-establish my reputation," he added.

Since Ginger White stepped forward Monday alleging a long-term affair, the allegation has overshadowed Cain's campaign.

He told The New Hampshire Union Leader that his wife, Gloria, his wife of 42 years, did not know he was providing the 46-year-old Atlanta-area businesswoman with money for "month-to-month bills and expenses."

"Unfortunately, I'm a softy and I feel sorry for people when they get in deep financial trouble, especially given this economy," Cain later told Fox News.

White told MSNBC in an interview Thursday night that she was "deeply sorry" for causing Cain's wife or other members of his family any pain.

Even before White surfaced, Cain faced steep hurdles to the nomination. He didn't have much of a campaign organization. He was spending more time on a book tour than in early primary and caucus states. And he was dealing with doubts about whether he was ready for the presidency, given a series of fumbles on policy questions.