Herman Cain is surging in Iowa. The last thing he needed was for old sexual-harassment allegations to come to light.

That’s no light accusation in Iowa, a state whose reputation as a bastion of socially conservative Republicans was cemented last cycle when evangelical darling Mike Huckabee pulled off a triumphant (and unexpected) caucus win. For Cain, who already gave some social conservatives pause with his remarks about abortion in mid-October, it is vital to put this issue to rest as soon as possible.

“If the story continues to develop late and there are elements of truth to it, it’s going to hurt him in Iowa,” says Bob Vander Plaats, who headed Mike Huckabee’s 2008 campaign in Iowa and currently is president of the Family Leader, a socially conservative activist group. “If he’s able to deflect these allegations as being just a result of somebody gaining public stature and somebody wants to take a shot at him, I think that’s part of the process.”

“If it isn’t true, as he says,” Vander Plaats adds, “and if the Restaurant Association is not commenting and the women basically can’t expand their story, it’s going to be hard to verify.”

For Cain, who is making a case that the presidency is an acceptable stage on which to make his political debut, winning one of the first two states is crucial to proving that he’s a serious candidate, and not merely using the GOP primary process as a substitute for an Oprah Book Club endorsement. Cain is polling second in New Hampshire, but is behind Mitt Romney by 22 points, according to the RealClearPolitics average of polls.

So to win early, Cain needs to keep the support of Iowa evangelicals, who are key to his high poll numbers in the state. “He’s leading the Des Moines Register poll, but if you read the internals on it, he was supported by 37 percent of born-again Christians,” notes Craig Robinson, editor of TheIowaRepublican.com and a former political director of the Iowa GOP. The combination of Cain’s “lack of clarity” on abortion in a series of interviews last month with these allegations jeopardizes his popularity with those voters, Robinson says. “Even the accusation is going to hurt him in Iowa.”

Richard Land, director of the Southern Baptist Convention’s Ethics and Religious Liberty Commission, observes that Cain must have “good answers” on the questions swirling around the allegations.

“I know sometimes conservatives complain that there is a double standard, but social conservatives ask to be judged by a double standard,” Land says. “We believe in family values. We believe in morality.”

But he does see a path forward for Cain. “I think that the people will give him the benefit of the doubt if he has answers that are credible,” Land comments. “The public likes him enough that they give him the benefit of doubt. If Newt Gingrich said we should electrify the fence, he’d be out of the race. But when Herman Cain says we should electrify the fence along the border, he says, look, you people need to get a sense of humor here. And it’s okay. That’s a gift.”

Cain’s comments on electrifying the border fence are part of a larger problem his campaign is facing — and a trend that can’t continue as the candidate addresses this story.

“This narrative is emerging with Herman Cain, that he’s not hitting things straight on, whether it’s his wandering abortion answer or regarding his answer on the electric fence,” says Tim Albrecht, communications director for Iowa governor Terry Branstad and Romney’s Iowa communications director last cycle. What Cain must do now is be straightforward and forthright, Albrecht warns. “If he dances around this issue, he’s not going to do well here.”

Vander Plaats also sees a penchant for changing explanations as Cain’s Achilles’ heel. “The comments that he made to Piers Morgan [on abortion], he had to walk that back and basically say what he meant to say. His comments on CNN about negotiating with terrorists, he had to walk that back. So he doesn’t want to develop a consistency for a pattern of these types of things, because that will continue to raise questions. You don’t want the voters going to caucuses with a lot of questions,” he says.

Cain must also resist the temptation to spin the accusations into a mainstream-media blame story, Iowa politicos warn. “I don’t think that flies,” says Robinson bluntly.

David Yepsen, a former Des Moines Register reporter who is now the director of the Paul Simon Public Policy Institute, says that while “[conservative] voters have no particular love for the media . . . this business of shooting the messenger just doesn’t pay long-term dividends for a candidate. It’s not going to go away.”

The timing is also delicate. “He’s at a very fragile time in his campaign. He’s starting to lift off,” Yepsen observes. “This is ice on his wings. He needs to get rid of this fast.”

Robinson also notes that the Iowa caucuses are just over two months away. “Herman Cain doesn’t have any record for voters to look at it. And when something like this comes up, it causes doubt. He’s got 62 days to soothe that doubt before the first people in this process vote. I don’t know if 62 days is long enough to calm people’s fears on who it is that they’re supporting.”

So far, however, Cain appears to be weathering the storm. The Des Moines Register called 20 likely Iowa GOP-caucus-goers yesterday and found that “none said the allegations had moved them to reject Cain as a potential pick.”

And Albrecht sees the unconventional nature of this cycle as a potential way for Cain to swat back this story. “I think this cycle has shown us that a week is an eternity,” he says, “so certainly there’s plenty of time.”

— Katrina Trinko is an NRO reporter.