WASHINGTON — The Senate Judiciary Committee inquired about at least one additional allegation of misconduct against Supreme Court nominee Brett Kavanaugh, according to a transcript of a phone call released by the committee Wednesday.

Republican Senate investigators asked Kavanaugh about the new complaint during a call on Tuesday between Kavanaugh and committee staff.

When asked about the allegation, contained in an anonymous letter sent to a GOP senator, Kavanaugh responded, “we’re dealing with an anonymous letter about an anonymous person and an anonymous friend. It’s ridiculous. Total twilight zone. And no, I’ve never done anything like that.”

While Republican staff posed questions to Kavanaugh, their Democratic counterparts were also on the call but did not ask any questions.

“We have no reason to assign the letter credibility," Taylor Foy, a spokesperson for Judiciary chairman Charles Grassley said. "And even if we did, we’d have no way to investigate the allegation as it was made anonymously and cannot be corroborated. The committee regularly receives anonymous letters, some of which are viewed with credibility, but many of which are not. To make sure no stone was left unturned, the committee asked Judge Kavanaugh yesterday about this anonymous letter. Judge Kavanaugh flatly denied any such event ever happened.”

The anonymous complaint that was sent to Republican Sen. Cory Gardner of Colorado, claimed that Kavanaugh physically assaulted a woman he socialized with in the Washington, D.C., area in 1998 while he was inebriated.

The sender of the complaint described an evening involving her own daughter, Kavanaugh and several friends in 1998.

“When they left the bar (under the influence of alcohol) they were all shocked when Brett Kavanaugh, shoved her friend up against the wall very aggressively and sexually.”

“There were at least four witnesses including my daughter.” The writer of the letter provided no names but said the alleged victim was still traumatized and had decided to remain anonymous herself.

A Democratic source said the minority wasn’t satisfied by the Republicans’ questions about the incident during the call, calling them cursory, and believed it should be investigated more deeply. But other Democrats downplayed its importance.

“Senate democrats are focusing on the allegations — serious and credible allegations — that include people who have come forward," a senior Democratic aide told NBC News. "Without the FBI's willingness to get involved, we can't investigate this claim further."

“Republicans may have leaked these in an attempt to make the others look frivolous by association,“ the aide said.

NBC News reached out to the White House for comment.

Kavanaugh, a federal judge who was nominated to the Supreme Court on July 9, has staunchly denied public allegations from three women alleging sexual misconduct.

On Wednesday, President Donald Trump said he could consider withdrawing Kavanaugh’s nomination if he “thought he was guilty of something like this.” Earlier Trump said the public accusations against Kavanaugh were false.

One of the accusers, Christine Blasey Ford, is set to testify before the committee Thursday. She has said that in 1982, when she and Kavanaugh were in high school, he pinned her down while they were in a suburban home in Maryland, attempted to remove her clothing and put his hand over her mouth when she tried to scream.

In a letter to the committee, Ford says that she thought she would be killed and that he had attempted to rape her. She has also said that Mark Judge was a witness and participant in the alleged assault. Kavanaugh has said it is possible he may have met her but he denied the accusation.

Sen. Mazie Hirono, D-Hawaii, who sits on the Judiciary Committee, would not say Wednesday whether there were any additional information she was aware of, but added, “there are certain areas that I’ve been interested in. He could be perjuring himself because of his response to my question about whether he had ever” engaged in sexual misconduct "as an adult. He could have perjured himself.”

A college classmate from Yale, Deborah Ramirez of Boulder, Colorado, has accused Kavanaugh of exposing himself and humiliating her at a party when they were in school together. Kavanaugh has said this incident didn’t occur.

On Wednesday, a third woman informed the Senate committee that she had been the victim of a gang rape in approximately 1982 in which she says Kavanaugh was present. The woman, Julie Swetnick, did not name Kavanaugh as an assailant.

Kavanaugh called this allegation “ridiculous,” and said he doesn’t know her.

A spokesman for Senate Judiciary Committee Chairman Chuck Grassley, R-Iowa, told NBC News that members of the panel will hold another phone call with Kavanaugh on Wednesday to ask him about Swetnick’s allegation. In two previous calls with Kavanaugh, he has denied allegations from Ford and Ramirez.

The calls are not under oath, but Kavanaugh will be reminded at the beginning of the call that lying to the Congress is against the law.

On Wednesday, Trump said he “can't tell” yet whether Kavanaugh’s known accusers are “liars” because he’s waiting to watch the hearing on Thursday. Trump admitted it’s “possible” they could be “convincing.”