A former boyfriend of Brett Kavanaugh accuser Julie Swetnick has told lawmakers that he does not believe her claims that she saw Kavanaugh engage in sexually inappropriate conduct as a high school student in Maryland.

In a letter released by Republicans on the Senate Judiciary Committee on Tuesday, Dennis Ketterer, a former TV weatherman in Washington and a onetime Democratic congressional candidate, wrote that Swetnick "never said anything about being sexually assaulted, raped, gang-raped or having sex against her will" and "never mentioned Brett Kavanaugh in any capacity."

In his four-page letter, Ketterer says that he and Swetnick had a brief relationship in the 1990s, while Ketterer was having "marital problems" and at a time when Swetnick was "very sexually aggressive with me." He claims that in 1996, he called Swetnick's father in a bid to get her number with a view to "possibly bringing her on to help with my campaign."

"He told me that he had psychological and other problems at the time ... and said I wouldn't want her to work on my campaign," wrote Ketterer, who added that Swetnick's father hung up the phone when he pressed him for more information.

According to Ketterer, he was motivated to come forward after watching Thursday's dramatic Judiciary Committee hearing featuring Kavanaugh and another accuser, Christine Blasey Ford.

"As I watched part of the [hearing], and saw Mrs. Kavanaugh looking so sad I felt she needed to know that in this instance, her husband was being mischaracterized," said Ketterer, who added that he was sexually assaulted when he was nine years old.

"My heart still feels heavy, for me as well as Julie and the Kavanaughs," Ketterer's letter concludes. "That said, based on my direct experience with Julie, I do not believe her allegations against Mr. Kavanaugh."

Swetnick's attorney, Michael Avenatti, said on Twitter that Ketterer's letter was "garbage" and showed that "the GOP is desperate."

"The allegations he makes are false and without any basis," Avenatti added. "We demand that the FBI interview my client & him, and that anyone found to have submitted false info be prosecuted to the fullest extent of the law."

In an interview with NBC News, Swetnick claimed that she saw Kavanaugh "paw on girls" and "[touch] them in private parts" at parties she attended in the early 1980s. However, she stopped short of saying he drugged or sexually assaulted her or other women. NBC News broadcast the interview Monday, but noted it had been unable to independently verify Swetnick's claims.

Kavanaugh has strongly denied allegations of sexual misconduct made by Swetnick, Ford and a former Yale classmate, Deborah Ramirez. The FBI is conducting a supplemental review of Kavanaugh's background focusing on those claims.