Media playback is unsupported on your device Media caption Ginger White told Good Morning America: "This was not sex for cash"

Herman Cain would not make a good president, says Ginger White, the woman who said she had a 13-year affair with the Republican White House hopeful.

Speaking to ABC News, Ms White also referred to her relationship with Mr Cain as "very casual".

The former pizza firm executive has denied the affair, calling Ms White a "troubled Atlanta businesswoman".

The candidate has said he is "reassessing" his campaign in light of the new allegations.

Ms White, 46, said on Wednesday that her mobile phone records show interactions with Mr Cain as late as November, although their relationship ended eight months ago when he began running for president.

"It was a very casual affair. Am I proud to admit to that? No I'm not," Ms White told ABC.

Mr Cain has not denied he was friends with Ms White, or that he helped her financially, but has denied they had any sexual relationship.

Analysis Whether he quits the race in the coming days, or soldiers on to Iowa, it still feels like game over for Herman Cain. With the sex allegations piling up, Republican voters have simply tired of this narrative. Notwithstanding his denials, Mr Cain is now damaged goods. As support and funds drain away, it would not come as a surprise to see him bow out soon, citing a need for privacy. Who benefits? The polls suggest a simple see-saw effect, in which Newt Gingrich rises as Herman Cain falls. Mr Gingrich, of course, has his own relationship baggage. But it seems many Republicans have factored in his past infidelity, and are focusing instead on the former Speaker's vast experience and powerful intellect. Conversely, Mitt Romney may hope that Mr Cain fights on, retaining a groundswell of support. That would further splinter the votes of anti-Romney conservatives.

Mr Cain, a former head of the National Restaurant Association, wrote to supporters on Tuesday: "I have helped many friends and acquaintances throughout the years... Ms White has made it apparent that she was abusing the friendship."

Ms White has said that Mr Cain never asked her to keep quiet about the affair.

"The funny thing about Herman Cain is never in a million years did he probably think that I would speak out on this," she said.

"And honestly speaking, I never wanted to."

Ms White said the affair took place over a 13-year period, describing it as an "on-and-off" relationship that included several trips, including to Las Vegas to see Mike Tyson fight Evander Holyfield.

Mr Cain has begun campaigning in Ohio this week, and made a speech to supporters on Wednesday, where he told supporters that there was "a groundswell of support" for him.

"They are attacking my character, my reputation, and my name, in order to try and bring me down," Mr Cain said.

'Too much of a cloud'

In recent weeks Mr Cain has also faced a series of allegations of sexual harassment dating from his time as head of a restaurant lobby group.

Mr Cain has denied the claims, but admitted a financial settlement was reached with one of his accusers, Karen Kraushaar.

Another woman, Sharon Bialek, went public with her accusation that Mr Cain groped her when she asked him for help finding a job.

Before the allegations began to emerge, the Georgia businessman had enjoyed a lead in several opinion polls.

But since then he has seen his ratings slip, while former House Speaker Newt Gingrich has surged.

In the event that Mr Cain quits the race, it is not clear which candidate would benefit most.

But Mr Gingrich rose to a new high in a Gallup opinion poll on Tuesday, while former Massachusetts Governor Mitt Romney, who has maintained the steadiest lead, was down.

In a conference call with campaign staff on Tuesday, Mr Cain said the latest allegation was a "cause for reassessment".

"We have to do an assessment as to whether or not this is going to create too much of a cloud, in some people's minds, as to whether or not they would be able to support us going forth."

He concluded by telling his team: "If a decision is made, different than to plough ahead, you all will be the first to know."