The accuser, Julie Swetnick, made the claims in an affidavit that was posted online by attorney Michael Avenatti. She alleges that the pair spiked party punch with drugs or grain alcohol to lower girls' inhibitions and says she witnessed boys including Kavanaugh and Judge lining up to gang-rape an inebriated girl.
A spokesman for Republicans on the Senate Judiciary Committee said they were reviewing the affidavit.
Mr Avenatti declined to expand on the allegation in an interview on ABC's The View, saying he would not add detail beyond what was in the statement. President Donald Trump also responded on Twitter, writing, "Avenatti is a third rate lawyer who is good at making false accusations, like he did on me and like he is now doing on Judge Brett Kavanaugh".
In written testimony before the Senate hearing, Kavanaugh says he never had a "sexual or physical encounter of any kind" with Ford and had never done anything "remotely resembling" the conduct she describes.
Ford says Kavanaugh pinned her on a bed and tried to take off her bikini while covering her mouth at a high school party. Only 12 percent of Democrats agreed that senators should confirm Kavanaugh if he sexually assaulted Dr. Christine Blasey Ford when both were in high school. She also says she was the victim of one of these rapes where Judge and Kavanaugh were present: "During the incident, I was incapacitated without my consent and unable to fight off the boys raping me". Kavanaugh denied the accusation soon after it was reported Sunday, Sept. 23, 2018, by The New Yorker magazine. If he will not, at the very least, the hearing and vote should be postponed while the FBI investigates all of these allegations. Chuck Grassley said the committee is now reviewing the document. Dianne Feinstein of California, that he saw no reason to delay Thursday's hearing with Kavanaugh and Ford amid the new allegations. The Supreme Court nominee will be sworn in and will then give his opening statement.
Republicans hold a 51-49 advantage in the Senate and can't afford more than one defection to ensure confirmation without Democratic support. However, Ford did not share her attacker's name with her husband until a couple's therapy session in 2012.
The statement came amid graphic new allegations that the nominee was involved in "gang" rapes in the 1980s, which Kavanaugh vehemently denies.