He told aides on Tuesday that he is evaluating whether the latest accusations "create too much of a cloud" for his Republican presidential candidacy to go forward.
On Monday, Ginger White, a Georgia businesswoman, told an Atlanta television station that she and Cain had an extramarital affair that ended shortly before his bid for the GOP presidential nomination.
White said she met Cain in the late 1990s while he was a high-ranking official at the National Restaurant Association. She claims that Cain would fly her to locations to meet with him, including a rendezvous to Palm Springs.
Cain has acknowledged knowing White for the time specified, but maintained that the relationship was strictly platonic.
"It was just a friendship relationship," he said, according to a transcript of a conference call made to his senior staff. "That being said, obviously, this is a cause for reassessment."
The recent allegation is among other accusations of inappropriate sexual behavior against Cain. He has been accused of sexually harassing, and in one case groping three women while at the National Restaurant Association over a decade ago.
White said what motivated her to come forward was the aggressive way Cain responded to the allegations of sexual harassment.
"It bothered me that they were being demonized, sort of, and being treated as if they were automatically lying, and the burden of proof was on them," she said. "I felt bad for them."
Cain has only committed to keeping his campaign schedule for the next several days.
Cain's popularity surged at one point among GOPs. But the allegations of sexual inappropriate behavior and flubs on foreign policy issues, such as the U.S. handling of Libya, has taken a toll on poll numbers.
The Associated Press contributed to this story.