The former boyfriend of one of his sexual harassment accusers came forward Monday, backing up her story.
"She said that something had happened and that Mr. Cain had touched her in an inappropriate manner," said Victor Zuckerman.
Hours after Zuckerman stepped forward to give his account, Cain's wife - Gloria - defended her husband publicly.
"That would have been something that was totally disrespectful of her as a woman, and I know that's not the person he is," said Gloria Cain.
At least three other women have claimed that Cain engaged in inappropriate sexual conduct toward them in the late 1990s when he ran the National Restaurant Association.
Adding to his problems this week: Cain's political gaffe during an interview. It was a straightforward question from the Milwaukee Journal Sentinel, but the answer, which was posted on YouTube, went viral.
Cain was asked if he agreed with President Barack Obama's Libya policy.
First there was a 10-second pause, and then clear discomfort. Cain then asked, "President Obama supported the uprising, correct?"
He went on to say, "I do not agree with how he handled it for the following reason. No, that's a different one."
He lost his train of thought, saying, "I got all this stuff twirling around in my head."
On Monday night, Cain did damage control in an unusual place: a football tailgate at Lambeau Field in Green Bay, Wisc.
"It was a pause. That's all it was. Good grief!" he said to reporters.
Cain's spokesman J.D. Gordon said that Cain had four hours of sleep because of a busy campaign schedule when he sat for the interview. He said Cain took his time answering because the candidate wanted to make sure he was focusing on the right problem.
Cain has dropped 11 points in the polls in the last few weeks. The biggest beneficiary of that is Newt Gingrich, who's now locked in a head-to-head matchup with Mitt Romney for first place.
The Associated Press contributed to this report.