Far from backing down, Cain has hired a fierce new lawyer to help him fight the four women's claims "in the court of public opinion." And he's pushing forward with a more aggressive campaign strategy to get his message out, airing his first television ad in Iowa and preparing to sign a lease on a cavernous new campaign office in Atlanta that will serve as a hub for volunteers.
Even so, there are signs that the accusations he sexually harassed women when he led a Washington trade group more than a decade ago could be causing Cain's luster to dim -- and uneasiness grows among Republicans less than two months before voting begins in Iowa.
Private polling shared with The Associated Press shows Cain's support has declined in Iowa since last month. Internal polls of likely Republican caucusgoers showed Cain's support consistent with The Des Moines Register's poll in late October, which showed Cain narrowly leading in Iowa with 23 percent. The private polls showed Cain's Iowa still in double digits, but markedly lower.
And the scandal was filtering down to the grassroots in Iowa where volunteers were proceeding with their nightly calls to potential supporters armed with a response to questions about the allegations.
Although the script of the calls was unchanged since before the allegations became public more than a week ago, volunteers were told to echo Cain's denial of wrongdoing.
"When we are trying to convince someone to be a team leader, we answer their questions," Cain's Iowa campaign chairman Steve Grubbs said. "The answer to that is: Tell them what Herman Cain is saying."
The Cain camp seemed to be making efforts to shore up support with women, rolling out the endorsement of a prominent female state GOP lawmakers in his home state of Georgia, Renee Unterman.
The Cain camp released his first TV ad of the season in Iowa and another web ad focused on his signature 9-9-9 tax overhaul plan.
And Georgia state director David McCleary said the campaign would sign a lease Friday for a new 4,200-square-foot office space that would coordinate Cain's volunteer efforts, with phone banks to call voters in early states like Iowa.
McCleary said that since the allegations broke "I've had more people call and volunteer, saying how can I help?"
Cain's new lawyer, Lin Wood, could provide polish and focus to a candidate who struggled to stick to a consistent version of events as the story broke.
In an interview with The Associated Press, Wood, an Atlanta-based lawyer whose high-profile roster of clients have included the family of Jon Benet Ramsey and wrongly-accused Olympic park bomber Richard Jewell, said he would helping the campaign "evaluate and respond to" the women's claims.
"Mr. Cain is being tried in the court of public opinion based on accusations that are improbable and vague," Wood told The AP. "The media -- bless your heart -- you turn our system of justice into one of guilt by accusation."
But privately, Republicans worry about Cain's impact on a nominating contest that's about to start in earnest. While no one is rushing to push him out of the race, the chorus is growing for the former pizza executive to explain the allegations of unwanted sexual advances that have come to light more than a decade after they are said to have happened.
"It's one of the he-said-she-said stories," said GOP strategist Greg Mueller. "But you want to put the story to rest as quickly as you can and let the voters decide. It seems like every day it's a new elevation of the story. Either that's going to peter out or it's going to solidify."
If that happens, it completely overshadows the GOP's message against President Barack Obama.
"We were talking about the role of government and how it's gone too far. We were putting some conservative principles on the table. That's when Republicans do well, when there is a clear line of distinction."
There will be more from Cain on Thursday, when his tour will take him at least to Ypsilanti, Grand Rapids and Traverse City, according to tea party organizers. Tea party backers make up the core of support for Cain, a former pizza executive and self-styled political outsider. And many have said in recent weeks that they do not give credence to the charges against Cain.
Four women have said Cain sexually harassed them in the 1990s when he was at the helm of the National Restaurant Association. Two have come forward publicly, including one who had filed a sex harassment claim.
Mention of the scandal at Wednesday night drew loud boos from the crowd. Cain brushed aside the allegations saying they'd helped boost his fundraising,
And fellow Republican front-runner Mitt Romney declined to take the bait and criticize Cain at the forum even though in a previous interview he'd called the allegations "particularly disturbing."
Still, even as he faced allegations of unwanted sexual advances against women, Cain stumbled on Wednesday night by mocking the first female House speaker Nancy Pelosi as "Princess Nancy."
During the CNBC debate, Cain said Pelosi -- now House minority leader -- blocked any effort when she was speaker of the House to repeal Democrats' health care overhaul, legislation she helped marshal through.
After the debate, he told CNBC he "probably should not have made" that comment.