Supreme court nominee Brett Kavanaugh is willing to testify before the Senate judiciary committee about an accusation he sexually assaulted a woman when they were teenagers in high school.
An attorney for Kavanaugh's accuser, Christine Blasey Ford, said she was also willing to testify.
Ford's allegation, made in the Washington Post on Sunday, plunged Kavanaugh's nomination into uncertainty days before the committee was due to vote. Republicans are under intensifying pressure to delay the vote; White House counselor Kellyanne Conway said on Monday Ford "will be heard".
Ford, 51, is a research psychologist at Palo Alto University in northern California. Speaking to the Post, she described an incident she said happened when she and Kavanaugh were in high school in the early 1980s.
She alleged that Kavanaugh and a friend - both "stumbling drunk" - corralled her into a bedroom at a party. Kavanaugh then pinned her on a bed, she said, groping her and placing his hand over her mouth. Ford said she was able to escape only when the friend jumped on top of them.
In a statement released by the White House on Monday, Kavanaugh said: "I have never done anything like what the accuser describes - to her or to anyone.
"Because this never happened, I had no idea who was making this accusation until she identified herself yesterday. I am willing to talk to the Senate judiciary committee in any way the committee deems appropriate to refute this false allegation, from 36 years ago, and defend my integrity."
Earlier on Monday, Ford's lawyer, Debra Katz, told NBC's Today Show her client was "willing to do whatever it takes to get her story forth".
Democrats have called for delay in Kavanaugh's nomination process. Republicans hope to confirm him before the midterm elections in November, when their Senate majority could be at risk.
Two Republicans on the judiciary committee - Jeff Flake of Arizona and Lindsey Graham of South Carolina - have said Ford should be heard.
Flake told Politico he was "not comfortable" voting to advance Kavanaugh without hearing first from Ford. His opposition could derail the committee vote.
Graham said the vote should not be delayed. "If the committee is to hear from Ms Ford, it should be done immediately," he said in a statement.
The Republican chair, Chuck Grassley, said it was "disturbing" that "uncorroborated allegations from more than 35 years ago, during high school, would surface on the eve of the committee vote". But later on Sunday a spokesman for the committee said the chairman was working to set up calls with Ford and Kavanaugh before Thursday.
Dianne Feinstein, the ranking Democrat, said: "There's a lot of information we don't know and the FBI should have the time it needs to investigate this new material. Staff calls aren't the appropriate way to handle this."
On Monday, Grassley criticised Feinstein's stance and said such calls were "standard procedure" and he would therefore "continue working to set them up". Feinstein and the nine other Democrats on the committee signed a letter demanding a delay.
Before the accusation surfaced, Republicans had been confident Kavanaugh would sail through the Senate. The only outstanding question was the support of two Republicans: Susan Collins of Maine and Lisa Murkowski of Alaska. Both have come under immense pressure from liberal organizations who fear Kavanaugh would overturn the Roe v Wade 1973 decision that legalized abortion. How Ford's accusation will affect their decision remains unclear.
On Monday, Collins wrote on Twitter: "Professor Ford and Judge Kavanaugh should both testify under oath before the Judiciary Committee."
The White House has sought to cast Kavanaugh as a champion for women. As the Ford allegation surfaced late last week, initially anonymously, a pro-Kavanaugh letter was published, signed by 65 women who said he had always "behaved honorably and treated women with respect".
The letter appears to have been orchestrated by confirmkavanaugh.com, a website funded by the Judicial Crisis Network, a group that relies upon undisclosed donations and has spent millions on campaigns to get conservatives into judicial positions.
The friend named in the Post report, the writer Mark Judge, said he had "no recollection" of the alleged events.
In an interview with Fox & Friends on Monday, Conway said it would be up to the Senate committee to decide if Ford speaks publicly or privately.
"Let me make this very clear," she said. "I've spoken to the president. I've spoken to Senator Graham and others. This woman will be heard."
Katz declined to tell NBC whether Ford, registered Democrat, believes Kavanaugh's nomination should be withdrawn. But she noted that her client had not wanted to come forward publicly and did so only after the accusations began to circulate late last week.
"This is not a politically motivated action," Katz said. "In fact she was quite reluctant to come forward."