[UPDATE - 11:18 p.m. ET] - NBC News reports "there are strong indications" that Herman Cain will announce tomorrow that he is dropping out of the presidential race. Per NBC's Andrea Mitchell, "while aides tonight deny that he has made up his mind, a source close to Cain says that he wants to protect his family from more fallout from the allegations that he is facing." NBC's video report can be viewed at the top of this article.
ORIGINAL REPORT BELOW:
By SHANNON McCAFFREY and PHILIP ELLIOTT, The Associated Press
ATLANTA (AP) -- Rapidly becoming a mere footnote in the presidential race, Herman Cain sent mixed signals Friday on whether he would abandon his beleaguered White House bid on Saturday after a woman's allegation of an extramarital affair.
He said he would make a "major announcement" on whether he would press on - at an event still being billed as the grand opening of a new headquarters.
It is the latest - and perhaps final - twist in a campaign saga that has taken the Georgia businessman from unknown longshot to surprise frontrunner to embattled tabloid subject.
He arrived at his suburban Atlanta home on Friday afternoon to talk with his wife of 42 years, Gloria, about whether to press on after his campaign was rocked by multiple sexual harassment allegations and this week's claim that he had a 13-year affair. He denies wrongdoing. It was their first face-to-face meeting since the allegation was made public.
As night fell, campaign aides who were optimistic earlier Friday that Cain would press on said privately they expected that he would exit the race.
Earlier, in a speech in Rock Hill, S.C., Cain wouldn't disclose whether he would drop out but told supporters to stay tuned. He said he would clarify the next steps of the campaign and assured backers the affair claim was "garbage." But he also said he needed to consider what he would do with campaign donations already banked if he dropped out of the race.
"Nobody's going to make me make that prematurely," Cain told a crowd of about 100 people. "That's all there is to it."
"My wife and family comes first. I've got to take that into consideration," Cain added. "I don't doubt the support that I have. Just look at the people who are here."
Cain had not seen his wife since Ginger White, 46, came forward and said she had a sexual affair with Cain that lasted more than a decade. He has said they were only friends but acknowledged that he helped pay her monthly bills and expenses. His wife, Cain said, did not know of the friendship with White.
The former Godfather's pizza executive said he is reassessing whether his presidential bid is still viable.
But it was difficult to imagine a path forward with just a month until the lead-off Iowa caucuses.
Polls suggest his popularity has taken a deep hit.
A Des Moines Register poll released Friday showed Cain's support plummeting, 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.
A political novice, Cain leveraged strong tea party support to hurtle to the front of the Republican pack in October casting himself as an anti-establishment outsider. His catchy 9-9-9 tax overhaul proposal helped his rise. But his effort soon lost altitude.
He fumbled policy questions, and his campaign has been reeling since it was revealed a little more than a month ago that the National Restaurant Association 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. And his campaign was taking some steps to blunt the drumbeat of allegations.
It unveiled a "Women for Herman Cain" webpage with testimonials from female backers, some urging him to stay in the race. It was led by Gloria Cain.
The candidate's wife - who's not been on the campaign trail - has drawn her own support as the allegations against her husband have piled up.
A Facebook page "I Stand With Gloria Cain" had attracted more than 400 supporters by Friday afternoon.
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."
Word of a pending announcement took some aides by surprise.
"I am learning this as you're learning it," said Cain's Iowa campaign chairman, Steve Grubbs, who met Thursday with campaign manager Mark Block.
The two outlined a December travel schedule for Cain, who began advertising on television again in Iowa on Friday.
As of Friday afternoon, Cain was scheduled to participate in the two Iowa debates this month, hold a media announcement in Iowa on Dec. 12 and tour the state at the end of the month.
"That's sort of the plan, very tentatively," Grubbs said. "All that could change."
Georgia supporters set to attend the Saturday event in Atlanta - billed as a headquarters celebration - were taken aback by the news that an announcement was coming.
"I have heard nothing," said state Sen. Josh McKoon, a prominent Cain backer who will stand with him Saturday.
Philip Elliott reported from Rock Hill, S.C. Associated Press writers Ray Henry in Atlanta, Thomas Beaumont in Iowa and Steve Peoples in New Hampshire contributed to this report.