The Georgia businessman planned to make the announcement Saturday at what was supposed to be a festive grand opening of a new headquarters in Atlanta, rented when Cain sat surprisingly atop the GOP pack.
With the candidate's poll numbers plummeting and fundraising stalled, some campaign aides said privately they expected him to exit the race. But Cain spokesman J.D. Gordon cautioned late Friday that no decision had been made.
A meeting with key staff members was expected early Saturday.
Cain returned to his suburban Atlanta home Friday and met with his wife, Gloria, the first time they have seen each other face to face since 46-year-old Ginger White came forward on Monday and said she and the Republican had carried on a 13-year relationship.
Cain has denied having an affair with White. He said the concern over the toll the allegations were having on his family as well as a candid assessment of whether his campaign could still attract the needed support would inform his decision on whether to press ahead.
On Friday night, even as Cain weighed whether his campaign would move on, volunteers were busy tacking up signs at his headquarters and a contingent of Secret Service agents was inspecting the site in advance of Cain's arrival there.
"We are moving ahead," said Cain's Georgia director David McCleary, who said he had talked to the candidate earlier in the day and describe him as "upbeat."
Cain, the former Godfather's Pizza chief executive who has never held elected office, rose to become an unexpected front-runner in the volatile Republican race just weeks ago. A self-styled outsider, Cain enjoyed strong tea party support from conservatives who viewed him as an alternative to Mitt Romney. His charisma on the campaign trail drew large and enthusiastic crowds.
But under the glare of the national spotlight he fumbled policy questions, leaving questions about whether he was ready for the presidency. Then it was revealed at the end of October that the National Restaurant Association had paid settlements to two women who claimed Cain sexually harassed them while he was president of the organization.
A third woman told The Associated Press that Cain made inappropriate sexual advances but that she didn't file a complaint. A fourth woman also stepped forward to accuse Cain of groping her in a car in 1997.
Cain has denied wrongdoing in all cases.
Polls suggest his popularity has suffered. A Des Moines Register poll released Friday showed Cain's support plunging, with backing from 8 percent of Republican caucusgoers in Iowa, down from 23 percent a month ago.
Fundraising has also fallen off. He issued an email appeal to supporters on Friday asking for donations, in an attempt to gauge whether his financial support has dried up.
"I need to know that you are behind me 100 percent," Cain told backers. "In today's political environment, the only way we can gauge true support is by the willingness of our supporters to invest in this effort."
On Friday, Cain urged backers in South Carolina to look past the allegations.
"There's a lot of garbage on the Internet. There's a lot of garbage out there on the TV. There's a lot of garbage out there about me, don't you know? There's a lot of misinformation out there. You have to stay informed and check out the facts for yourself," Cain said.
He added: "I'm on this journey for a reason. I don't look back."