Story highlights Carl DeMaio has won national name recognition as a "new generation Republican".

Todd Bosnich is a former campaign staffer accusing DeMaio of sexual harassment.

DeMaio says Bosnich's version of events is a cover story for a suspected criminal.

DeMaio is challenging Rep. Scott Peters, a vulnerable first-term Democrat.

Charges of sexual misconduct, plagiarism and burglary have pitted a former staffer against a high-profile congressional candidate just weeks before the midterm elections.

The drama is unfolding in a city that just weathered a sexual harassment scandal ending the career of its Democratic mayor. The latest accusations by a former campaign aide could derail the career of up-and-coming Republican Carl DeMaio.

In a story of charges and counter charges, the one constant is this: they both insist the other is lying.

DeMaio has won national name recognition as a "new generation Republican," calling on his party to ditch social issues and winning plaudits for helping the Grand Old Party shed what many see as its intolerant image.

The openly gay, former San Diego city councilman has won support from GOP heavyweights like Senate Republican Leader Mitch McConnell, House Speaker John Boehner and even former New York City Mayor Michael Bloomberg.

But behind the scenes, things are much messier. DeMaio's former campaign policy director is accusing the candidate of sexual harassment, even saying DeMaio masturbated in front of him. DeMaio vehemently denies the allegations, saying they're the cover story of a plagiarist and suspected criminal.

This is not the first time DeMaio has been accused of sexually inappropriate behavior. Last year, a fellow city councilman said he twice caught DeMaio masturbating in a city hall restroom -- an allegation DeMaio denied.

THE CHARGES

Todd Bosnich says he joined DeMaio's campaign last year eager to work for a candidate who shared his values and who, like himself, is an openly gay Republican.

But Bosnich said his enthusiasm for his boss was soon replaced by dread, because DeMaio would find him alone and make inappropriate advances, massaging and kissing his neck and groping him.

One morning last April, Bosnich said he arrived early at campaign headquarters and DeMaio called him back to his office.

"I came over to his office, door was open. And he was masturbating," Bosnich said. "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."

There was no mistaking what was happening, he said.

Bosnich said the harassment that culminated that spring morning started months before, when DeMaio drove Bosnich back to his car after drinks with the staff at a local bar.

"We were making small talk on the way back. And when he pulled up to my car, he reached over into my lap and grabbed my crotch. And I flipped out. And I pushed his hand away," Bosnich said. "I just was shocked because I'd never had anyone do something like that to me, especially in a position of authority and trust. And, at the time, I just figured, well, maybe he was drunk and blew it off. But he progressively and progressively, the inappropriate touching incidents continued from there."

It was several more months, Bosnich said, before he mentioned the behavior to campaign manager Tommy Knepper, who laughed it off.

"'That's just the way Carl is,'" Bosnich recalls Knepper saying. "And that if I really felt that uncomfortable I shouldn't have let him know that I'm a gay man."

Knepper, Bosnich said, was blaming him.

"He was implying that it's my fault, that it's incumbent on me to stop Carl DeMaio from these behaviors," Bosnich said. "And I was really offended."

It wasn't until a few weeks after the masturbation incident, Bosnich said, that he confronted DeMaio, telling him to either stop the harassment or drop out of the race.

"It was the very next day, in the morning, that the campaign manager called me into his office and said that Carl lost his trust in me and that he'd terminated me," Bosnich said. "He offered me a position in the county Republican Party and also told me to sign a non-disclosure agreement in exchange for $50,000."

Bosnich said he considered the offer "an attempt to bribe me to keep my silence."

He left the campaign, he said, without taking any money or signing any papers. A day before the primary, Bosnich recorded an interview with a local conservative radio station outlining his allegations, but the interview never aired.

AND COUNTER CHARGES

After hearing that unaired interview, CNN asked DeMaio about Bosnich's allegations. He denied them.

"This is an individual that was let go by our campaign manager for plagiarism. A well-documented plagiarism incident of taking a report from the National Journal and passing it off as his own work," DeMaio said. "He was terminated. He admitted that he plagiarized. He apologized for plagiarizing and when we told him he was no longer welcome in the staff and in the campaign office, even as a volunteer, he left. Days later, he broke in."

DeMaio claimed the San Diego Police Department is investigating Bosnich for breaking into his campaign headquarters, smashing computers and cutting phone lines just days before the primary.

"It's unfortunate. He's clearly troubled. He got caught for the damage that he did to the campaign and now he's manufacturing in essence a cover story to explain away his actions," DeMaio said. "It's unfortunate. It's untrue. And my hope is that the police department will hold him accountable for his actions against our campaign."

During the interview, DeMaio said he could provide evidence that would refute Bosnich's claims and show that the former staffer was behind the break-in. However, DeMaio later offered to briefly share the documents only if CNN agreed not to report it. On its own, the material did not appear to refute Bosnich's claims.

The San Diego Police Department recently forwarded its completed investigation into the break-in to the district attorney, who is reviewing it, according to spokesmen for the police department and district attorney's office. But four months after the break-in, police still have not charged anyone or named any suspects.

A police spokesman said in an email that DeMaio identified two former staff members as potential suspects and Bosnich confirmed he was interviewed by police. But he denied breaking into DeMaio's office.

TRYING TO GET ANSWERS

After interviewing Bosnich on camera, CNN repeatedly tried to get detailed answers from DeMaio's campaign. Last week, CNN officials participated in a conference call, which they were led to believe would be an opportunity to ask questions. Instead, the call was led by hired consultant Richard Grenell, a former Mitt Romney presidential campaign spokesperson and Fox News contributor. Grenell refused to answer questions and accused CNN of being on a partisan witch hunt.

The next day, CNN sent the campaign a detailed list of questions, including whether the campaign manager knew about Bosnich's complaints. CNN was then contacted by high-powered Washington attorney Ben Ginsberg, who counseled both the Romney and George W. Bush presidential campaigns. Ginsberg said he would be handling CNN's questions. Ginsberg asked for more time and information before responding.

CNN's attorney granted Ginsberg more time and sent a second letter laying out the information that prompted the inquiries. Ginsberg then responded to CNN by saying its reporters needed to contact the campaign manager. Back to square one.

Nine days after seeking answers to our follow-up questions, the campaign manager, Knepper, sent a statement that was almost exactly what DeMaio said when we first asked him about the allegation weeks ago.

"These allegations are completely false. The individual making the claims was fired from the campaign months ago for plagiarism," Knepper said. "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."

PREVIOUS ALLEGATIONS

This is not the first time DeMaio has been accused of sexually inappropriate behavior. Last year, a fellow city councilman, Ben Hueso, said he twice caught DeMaio masturbating in a semi-private city hall restroom accessible only to city officials.

The Democrat declined an interview request, but councilwoman Marti Emerald said she learned about the 2009 incident immediately after Hueso witnessed it. On the way to the women's room, she said she literally bumped into Huseo as he exited the men's room across the hall.

"He was furious; he looked like something serious had just happened," Emerald said. "He said DeMaio was in there (masturbating). And I said do you want to grab a police officer and have him arrested? Because this is a violation of the (city) code. He said no, but he was pretty upset."

It's a claim DeMaio denied — even saying he took a polygraph test to support his denial, but he declined to provide the results to CNN.

"This lie crossed the line. It's so gross. It's so untrue. It's so humiliating that it demands a response," DeMaio said last year.

Bosnich also took an independent lie detector test to support his allegations, a copy of which Bosnich's attorney provided to CNN. The report said Bosnich's answers were "truthful" and found "no deception."

"It corroborated my account of being sexually harassed by Carl DeMaio," Bosnich said.

Bosnich also denied that he was the one who plagiarized from National Journal.

"Carl authored the report. And I offered input on it. But in terms of the final draft, in terms of the, even the composition of it, that was from Carl, as he admitted to the National Journal," he said.

At the time, DeMaio told National Journal that while his staff produced the report at his direction, he didn't know how much had been lifted. But he took full responsibility and told the Beltway publication, "I don't throw my staff under the bus."

The charges of sexual harassment echo those brought against another San Diego politician, Mayor Bob Filner. The Democrat was forced to step down last year after allegations of sexual harassment by 18 women.

DeMaio lost to Filner in the 2012 mayor's race and tried to make Filner's behavior an issue during a debate.

"You need a mayor who respects women. You need a mayor who sets that tone," he said then. "And you need a mayor who is willing to insist on zero tolerance when it comes to the issue of sexual harassment in the workplace and in any other environment."

This time around, it's DeMaio who's fending off charges of sexual harassment as he vies to replace Rep. Scott Peters, a vulnerable first-term Democrat.