Just as the sexual harassment allegations against him were beginning to fade, Herman Cain was faced on Monday with a new scandal when a Georgia businesswoman claimed to have had a 13-year affair with him -- and now The National Review and The Associated Press are reporting that he is reassessing whether to stay in the race for the Republican presidential nomination.

A spokesman for Cain's campaign told AP earlier on Tuesday that Cain would definitely continue his campaign. But according to National Review reporter Robert Costa, Cain told his senior staff in a conference call Tuesday morning that he would decide his next steps over the next several days.

Cain's poll numbers have already fallen precipitously in response to reports, first published by Politico in late October, that two National Restaurant Association employees received five-figure settlements after accusing then-CEO Cain of sexual harassment, and in response to subsequent sexual harassment allegations from two other women.

An Oct. 25-31 Quinnipiac poll showed Cain leading Mitt Romney by 7 points nationally, 30 percent to 23 percent. But in a Nov. 14-20 Quinnipiac poll, his support had fallen by more than half to 14 percent, putting him in a distant third place behind Newt Gingrich (26 percent) and Romney (22 percent).

Already, there were doubts about whether Cain could recover, and the latest allegations, whether true or not, only increase those doubts -- especially because his alleged mistress has more evidence to back up her story than previous accusers did.

Another Accusation, Another Denial

Ginger White, 46, told Fox 5 News that she met Cain in the late 1990s, when he was CEO of the National Restaurant Association. She claims that he invited her back to his hotel room after giving a speech in Louisville, Ky., and that they began a sexual relationship that lasted for the next 13 years. He also allegedly flew her out to various cities where he was speaking, put her up in fancy hotels and lavished her with gifts, Fox reported.

It wasn't complicated, White said. I was aware that he was married, and I was also aware I was involved in a very inappropriate situation. [But] he made it very intriguing. It was fun. It was something that took me away from my humdrum life at the time.

Cain denied the affair preemptively when he found out that White planned to go public with her allegations. He acknowledged that he knew White but said they never had a romantic or sexual relationship.

Here we go again, he told CNN on Monday. I didn't do anything wrong.

As evidence of the alleged affair, White offered her phone bills, which listed 61 calls and text messages -- some sent as early as 4:26 a.m. -- from a number she said was Cain's personal cell phone.

The Fox 5 reporter confirmed that the number belonged to Cain when he sent a text message and the candidate called back.

Cain claimed his number was in White's phone because he had been helping her financially, not because they were having an affair. But he also acknowledged that neither his wife nor any other family member knew White, which some commentators find suspicious.

Evidence Is Building

The best that can be said of Cain ... is that he has a poor memory for women and sexual harassment suits, behaved in ways that disturbed some NRA colleagues, and concealed from his wife a 13-year friendship that included financial assistance and frequent phone contact, sometimes at odd hours, William Saletan wrote on Slate.com. Further documents -- Kraushaar's lawsuit, her job performance reviews, Bialek's hotel records, White's flight purchase records, Cain's text or phone messages to White -- could make Cain's predicament much worse.

Saletan was referring to Karen Kraushaar, one of the former National Restaurant Association employees who received a settlement after accusing Cain of harassment, and to Sharon Bialek, who alleges that Cain tried to grope her after she asked him for help finding a job.

Cain has said that Kraushaar was fired because her job performance wasn't up to par, but her boss at her next job told CNN that Kraushaar was one of the hardest-working individuals I have ever known. He said that he had never seen Bialek in his life until she held a press conference this month, but a radio host who attended a Tea Party event in September told The Chicago Sun-Times that she saw Cain and Bialek talking and hugging at the event.

And, as Saletan noted, the purchases Cain allegedly made for Bialek and White are traceable, and if they exist, they surely will be traced in the coming days or weeks.

White said that her relationship with Cain was consensual, that he never mistreated her, and that she had always intended to keep it secret -- until, she said, she saw how Cain had responded to the women who accused him of sexual harassment.

It bothered me that they were being demonized, sort of -- they were treated as if they were automatically lying, and the burden of proof was on them, she said. I felt bad for them.

A Matter of Public Concern

In addition to denying White's allegations, Cain is arguing that they are not the public's business.

Cain has no obligation to discuss these types of accusations publicly with the media, and he will not do so even if his principled position is viewed unfavorably by members of the media, his lawyer, Lin Wood, said in a statement to Fox 5 news. This is not an accusation of harassment in the workplace -- this is not an accusation of an assault -- which are subject matters of legitimate inquiry to a political candidate. Rather, this appears to be an accusation of private, alleged consensual conduct between adults -- a subject matter which is not a proper subject of inquiry by the media or the public.

But the allegations will be a subject of inquiry whether they should be or not, and Cain's Tuesday morning conference call shows that he knows that. It could be a matter of days until we know whether his campaign will survive.