Embattled presidential candidate Herman Cain is expected to announce Saturday whether he will continue his campaign in the wake of an accusation that he conducted a 13-year extramarital affair.

At a town hall in South Carolina on Friday afternoon, Cain said he will be making an announcement to “clarify what the next steps are.” A news conference had previously been scheduled for Saturday to highlight the opening of his national headquarters in his home town of Atlanta, as well as the announcement of his campaign’s freshly minted senior leadership team for Georgia.

On Friday, Cain’s campaign also quietly invited some of his supporters and donors to Atlanta on Saturday for a meeting in which he will give them advance word of whether he intends to continue his campaign, said individuals close to the campaign.

One adviser who has been summoned to the private session said he believes that Cain is likely to announce he is ending his candidacy.

Another who has been invited to the morning meeting says attendees have been told he has made no decision, but wanted to meet with some of the supporters to express his gratitude.

In an apparent signal that it had not given up the fight, the campaign Friday announced the creation of “Women for Cain,” a group headed by Cain’s wife, Gloria, and designed to “inspire a national women’s alliance in support of Herman Cain for 2012,” according to the campaign’s Web site.

But the group quickly found itself being ridiculed after media organizations noted that the photo of four women giving the thumbs-up signal on the Web site was not an image of Cain supporters, but a stock photo. It subsequently removed the photo from the site.

Cain, the former chief executive of Godfather’s Pizza, enjoyed a brief reign at the top of the polls, in part because rank-and-file Republican voters viewed him as a refreshing outsider.

However, his campaign stumbled in early November, when Cain was accused of sexually harassing several women during his stint as head of the National Restaurant Association in the 1990s.

Cain has also committed a number of gaffes, including an excruciating interview with the Milwaukee Journal Sentinel editorial board, in which the man who is running to be commander in chief appeared to be unacquainted with U.S. policy toward Libya.

The latest setback came earlier this week, when an Atlanta woman, Ginger White, went public with an accusation that she and Cain had conducted a 13-year consensual extramarital affair. She produced phone records indicating they had been in contact dozens of times.

Cain has since acknowledged giving White money to help her through difficult financial times. However, he has repeatedly denied that he and White had a sexual relationship.

Cain returned Friday to Atlanta, where he was to have his first face-to-face meeting with his wife since White made her allegation. On Thursday, he told Fox News: “If my wife says terminate the campaign, would I quit? Yes.”

Steve Grubbs, who is overseeing Cain’s Iowa operation, said new numbers from the Des Moines Register’s new Iowa poll are “not good” and are consistent with the campaign’s internal analysis of the state of play there.

The poll showed Cain’s support at 8 percent among likely Republican caucus-goers, dropping from the 23 percent he enjoyed when the poll was last conducted in late October. The paper said it would report the other candidates’ standing in the poll on Saturday night.

Grubbs said he believes Cain can still finish in the top three in the Iowa caucuses. He acknowledged that Cain is now trailing well behind former House speaker Newt Gingrich and former Massachusetts governor Mitt Romney, after being at or near the top of the field. The campaign’s internal numbers show other candidates were either tied with Cain or running behind, he said.

Grubbs said Friday morning he had no inside knowledge of Cain’s plans and is continuing to focus on the organization in Iowa.

“If I could have a couple of drama-free weeks, I think we could get back on track,” Grubbs said.

Chief correspondent Dan Balz contributed to this report.