In one of the hottest House races in the country, a top Republican recruit has become mired in a dispute over sexual harassment allegations, presenting the GOP with a high-profile distraction in one of its best pickup opportunities.

Former San Diego Councilmember Carl DeMaio is a Republican running against freshman Democratic Rep. Scott Peters in a San Diego-based district. One of DeMaio’s former staffers, Todd Bosnich, sat down for an interview with CNN in which he described in vivid detail his harassment allegations. DeMaio has denied Bosnich’s allegations.

“I came over to his office, door was open. And he was masturbating,” Bosnich told CNN in an interview that aired Friday. “I saw his hand, his penis in his hand and he had a smile on his face. And as soon as I came over, he was looking at me.”

CNN’s Chris Frates confronted DeMaio, who reportedly offered to provide evidence to refute the former aide’s allegations. But the reporter said DeMaio only offered to share the documents if CNN did not report on the situation, and “on its own, the material did not appear to refute Bosnich’s claims.” At one point, CNN was contacted by Washington attorney Ben Ginsberg. After requesting more time, he eventually directed the reporter back to the campaign manager.

Bosnich also told CNN that after he confronted DeMaio about the alleged harassment, he was let go from the campaign and offered $50,000 to sign a non-disclosure agreement.

National Republicans are standing by their candidate.

“We fully support Carl DeMaio and we don’t make decisions based on unsubstantiated claims,” said Andrea Bozek, communications director of the National Republican Congressional Committee.

But the allegations surfaced just as vote by mail ballots were sent to thousands of voters in the district. And if the dust-up gains traction, DeMaio could see the ground shift from underneath him. The race is rated a Tossup by the Rothenberg Political Report/Roll Call.

“About somewhere in the neighborhood of 60-plus percent of the ballots cast in this election will be cast by mail, by absentee ballot, and a significant fraction of those votes are going to be cast over the next week or 10 days,” said Tom Shepard, a California Republican operative who doesn’t support DeMaio’s bid. “It’s not whether this story gets out, it’s when it gets out.”

“All of our campaign members, including myself, freely provided information,” DeMaio said at a Wednesday news conference at his campaign headquarters. “And the police chief called me and she said, ‘thank you for your full cooperation’ and we consider this matter closed.”

DeMaio’s campaign said Bosnich was fired after he allegedly plagiarized a report from National Journal that DeMaio claimed as his own back in May. DeMaio’s campaign also alleged Bosnich is a suspect in an alleged break-in at DeMaio’s campaign headquarters a few days before California’s June 3 primary. Thousands of dollars worth of computers, printers, telephones and an Internet router were destroyed in the incident. An attempt to reach Bosnich was unsuccessful.

“These allegations are completely false. The individual making the claims was fired from the campaign months ago for plagiarism. The individual only made these false allegations after the San Diego Police Department started investigating him as the suspect for the campaign office break-in,” said Dave McCulloch, spokesperson for the DeMaio campaign.

Spokespeople for the San Diego Police Department and the San Diego District Attorney’s office declined to comment on whether an investigation took place, and if so, where it currently stands.

But Democrats in the district have raised questions about potential conflicts of interest between DeMaio the district attorney, Bonnie M. Dumanis. Dumanis would be responsible for bringing charges stemming from the investigations, if necessary. She also endorsed DeMaio’s failed mayoral bid in San Diego in 2012. And last April, DeMaio hosted a $250 per head fundraiser for Dumanis’ re-election.

DeMaio is touted by national Republicans as a top recruit to take on Peters in this district, which President Barack Obama carried by a 6-point margin in 2012. Speaker John A. Boehner is slated to attend a Saturday fundraiser in California with DeMaio. A Boehner spokesman did not return a request for comment Friday on whether the fundraiser is still scheduled.

Millions have already been spent here on both sides of the aisle.

“I know a lot of consultants say you throw these things out fast and furiously at the last few moments,” said former Rep. Brian Bilbray, the Republican who lost the seat to Peters in 2012, and who is supporting DeMaio. “I hope the voters look at this with enough sophistication not to let their gut feeling be manipulated.”

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