A third woman is expected to publicly make accusations of sexual misconduct against supreme court nominee Brett Kavanaugh this week, her attorney Michael Avenatti said, plunging the judge’s confirmation to America’s highest court into further uncertainty.

“She reached out to me. We vetted her claim and she satisfactorily passed that vetting,” Avenatti said of the new accuser in an interview with the Guardian on Monday.

Avenatti said the woman has also asked to testify at a hearing before the Senate judiciary committee on Thursday, which will hear from California professor Christine Blasey Ford, who has alleged the judge drunkenly sexually assaulted her while in high school.

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The fresh allegations relate to Kavanaugh’s school days when he attended the elite Georgetown prep school in Maryland, where Ford has already accused him of a violent sexual attack at a party there when he was 17 and she was 15. Those allegations turned his confirmation process upside down earlier this month.

A second accuser, Deborah Ramirez, came forward Sunday to say that Kavanaugh exposed himself to her at a party when he was a freshman at Yale.

Matters relating to the additional individual date back to Georgetown preparatory school, Avenatti said.

“I’m going to be representing her and I may be representing some corroborating witnesses, and we plan on releasing additional information,” he told the Guardian.

Avenatti is better known as the combative, anti-Trump lawyer representing Stormy Daniels, who made her name as an actor and producer of pornographic films. Daniels is involved in multiple civil cases with the president and his one-time lawyer, Michael Cohen, over her account that she had an affair with Trump in the past. Trump denies the affair but paid Daniels hush money before the 2016 election to stay quiet about it.

Avenatti pointed out on Twitter on Monday morning that his new client is currently planning on identifying herself publicly prior to the expected hearing on Thursday.

He called for her to be able to testify before the Senate judiciary committee, which is holding Kavanaugh’s confirmation hearings, and also demanded that the committee question Mark Judge, a contemporary of Kavanaugh’s at Georgetown whom Ford says was involved in the alleged assault upon her.

Avenatti tweeted on Sunday evening that: “I represent a woman with credible information regarding Judge Kavanaugh and Mark Judge. We will be demanding the opportunity to present testimony to the committee and will likewise be demanding that Judge and others be subpoenaed to testify. The nomination must be withdrawn.”

Michael Avenatti (@MichaelAvenatti) I represent a woman with credible information regarding Judge Kavanaugh and Mark Judge. We will be demanding the opportunity to present testimony to the committee and will likewise be demanding that Judge and others be subpoenaed to testify. The nomination must be withdrawn.

Within minutes on Sunday night, Avenatti had been contacted by Mike Davis, the chief counsel for nominations for the judiciary committee, asking that any additional information “be submitted so that Senate investigators may promptly begin an inquiry”.

Avenatti replied that he was aware of significant evidence of Kavanaugh and Mark Judge, in summary, participating in “the targeting of women” with alcohol or drugs at house parties in the Washington DC-area in the early 1980s “in order to allow a ‘train’ of men to gang rape them”.

Avenatti then posted: “Senate investigators should pose the following questions to Judge Kavanaugh without delay and provide the answers to the American people,” and then listed detailed questions, including: “Did you ever target one or more women for sex or rape at a house party? Did you ever assist Mark Judge or others in doing so?”

On Monday he further posted that his new client has previously worked within the state department, the US Mint and the Department of Justice and has been granted multiple security clearances in the past. “The GOP and others better be very careful in trying to suggest that she is not credible,” he added.

Avenatti acknowledged that the list of detailed, questions about various aspects of the alleged sexual misconduct which he thought the committee should ask Kavanaugh, were noticeably specific.

“They are very pointed because they are designed to elicit answers that go directly to the facts,” he said.

Senate majority leader Mitch McConnell described the various and growing accusations against Kavanaugh as “a choreographed smear campaign”. Trump once again spoke in support of his ultra-conservative nominee, who had appeared to be sailing towards an almost certain, if controversial, confirmation until Ford’s allegations emerged.

A defiant Kavanaugh on Monday wrote a letter to committee chairman and Republican Chuck Grassley and ranking Democrat Diane Feinstein, saying: “I will not be intimidated into withdrawing from this process. The coordinated effort to destroy my good name will not drive me out... The last-minute character assassination will not succeed.”