It also forced the White House and Senate Republicans onto the defensive and fuelled calls from Democrats to postpone further action on his confirmation.

The new accusation landed late on Sunday in a report from The New Yorker, just a few hours after negotiators had reached an agreement to hold an extraordinary public hearing Thursday for Kavanaugh and Christine Blasey Ford, who accuses him of sexually assaulting her at a party when they were teenagers. Kavanaugh denies the claim.

The second claim against Kavanaugh dates to the 1983-84 academic year, which was his first at Yale University. Deborah Ramirez described the incident after being contacted by The New Yorker magazine. She recalled that Kavanaugh exposed himself at a drunken dormitory party, thrust his penis in her face, and caused her to touch it without her consent as she pushed him away.

In a statement provided by the White House, Kavanaugh said the event "did not happen" and that the allegation was "a smear, plain and simple." A White House spokeswoman added in a second statement that the allegation was "designed to tear down a good man."

Senator Dianne Feinstein of California, the ranking Democrat on the Judiciary Committee, called for the "immediate postponement" of any further action on Kavanaugh's nomination.

Republicans on the Senate Judiciary Committee said they would investigate Ramirez's accusation. Taylor Foy, a Judiciary spokesman, complained that Democrats "actively withheld information" from the Republicans. He said they appear "more interested in a political takedown" than a bipartisan process.

The New Yorker said it contacted Ramirez after learning of a possible involvement in an incident with Kavanaugh. It said that the allegation came to the attention of Democratic senators through a civil rights lawyer. The Democrats then began investigating.

Ramirez was reluctant at first to speak publicly "partly because her memories contained gaps because she had been drinking at the time of the alleged incident," The New Yorker reported.

After "six days of carefully assessing her memories and consulting with her lawyer, Ramirez said that she "felt confident enough of her recollections" to speak publicly, the report said.

Joining the maelstrom, Michael Avenatti, the attorney representing porn actress Stormy Daniels in her legal fight with President Donald Trump, claimed to represent a woman with information about high school-era parties attended by Kavanaugh and urged the Senate to investigate.

Avenatti told The Associated Press that he will disclose his client's identity in the coming days and that she is prepared to testify before the committee, as well as provide names of corroborating witnesses.

The accusation from Ramirez raise the stakes further for a dramatic showdown on Thursday, as Kavanaugh and Ford testify in public about an incident she characterises as attempted rape - and that he says simply never happened.

Australian Associated Press