[Read our story debunking 5 viral rumors about Judge Kavanaugh’s accusers.]

On Wednesday afternoon, more than 60 classmates from Georgetown Prep and women from sister schools who say they knew Judge Kavanaugh in high school signed a letter to rebut Ms. Swetnick’s allegations and deny ever having met her. “We never witnessed any behavior that even approaches what is described in this allegation. It is reprehensible,” said the letter, which was addressed to members of the Senate Judiciary Committee. “Brett Kavanaugh is a good man. He has always treated women with respect and decency.”

Mr. Avenatti had been using his Twitter account for days to promote what he said would be explosive allegations against Judge Kavanaugh. And immediately after he shared what he called a sworn affidavit from Ms. Swetnick, it drew immediate coverage across social media and cable news as another revelation to rock the confirmation process.

Asked in a brief interview why Ms. Swetnick would be attending parties with high schoolers during her college years, Mr. Avenatti said that the parties in question included people of both high school and college ages.

Mr. Avenatti said he had corroborating witnesses who could back up Ms. Swetnick’s accounts, but was not ready to present them because he was waiting to see if the Senate Judiciary Committee would begin a full investigation into her claims as he demanded, along with an F.B.I. inquiry. In her statement, Ms. Swetnick said she would be willing to appear before the committee.

In an email to Mr. Avenatti on Wednesday afternoon, Mike Davis, the committee’s chief nominations counsel, offered to arrange an interview with Ms. Swetnick.

“Please let me know immediately whether your client will agree to an interview by committee investigators today,” Mr. Davis wrote in the email, which was obtained by The Times. “We can do a telephone interview anytime this afternoon or evening.”

In recent days, Judge Kavanaugh and Mr. Trump, who nominated him in July, have been pushing back against the allegations relating to Judge Kavanaugh’s treatment of women. Mr. Trump called the claims a “con game” by Democrats who were “trying to delay and obstruct his confirmation.”