WASHINGTON (BLOOMBERG) - Dr Christine Blasey Ford said she is "one hundred per cent" certain that Supreme Court nominee Brett Kavanaugh is the person who sexually assaulted her when they were teenagers, and she told a Senate committee that he and his friend laughed at her expense during the attack.

Speaking publicly for the first time about allegations that could derail Mr Kavanaugh's nomination and redefine the "Me Too" era, Dr Ford she conceded that she could not remember every detail, but did not waver on her core accusation.

She wrapped up her testimony at about 2.15pm Washington time.

Mr Kavanaugh, who will testify later on Thursday (Sept 27), has strongly denied allegations of sexual misconduct.

"With what degree of certainty do you believe Brett Kavanaugh assaulted you?" Democratic Senator Dick Durbin of Illinois asked Dr Ford during a Senate hearing that could determine whether the nominee is confirmed to the high court.

"One hundred per cent," she responded.

Dr Ford also told a nationally televised Judiciary Committee hearing her accusation was "absolutely not" a case of mistaken identity. She said the 1982 incident was "seared into my memory" even though she doesn't remember all the details.

It was the first time the American public saw the person whose accusations had dominated the headlines for weeks, having only seen her before mostly in a single grainy photo in which she was wearing sunglasses. Her nerves were evident, and her voice cracked during her testimony.

Seating Mr Kavanaugh on the nation's top court - or not seating him - could affect the fight for control of Congress in the Nov 6 election. Republicans are looking for Mr Kavanaugh to cement a conservative majority on the court, while Democrats say he could provide the fifth vote to overturn the Roe versus Wade decision that legalised abortion.

President Donald Trump was watching the hearing from Air Force One, White House Press Secretary Sarah Sanders said. He hasn't talked to Mr Kavanaugh in a couple of days, she said.

The California psychology professor said the incident has "haunted me episodically as an adult".

She said she was "terrified" to testify before the committee and that she she "agonised daily" about whether to come forward with her claim.

Dr Ford said Mr Kavanaugh's friend, Mr Mark Judge, was in the room during the attack and that the two were laughing at her. She said she had an "indelible" memory of "the uproarious laughter between the two, and their having fun at my expense".

Senate Richard Blumenthal, a Connecticut Democrat, brought Dr Ford to tears when he thanked her for coming forward.

"If we agree on nothing else today, I hope on a bipartisan basis we can agree on how much courage it has taken for you to come forward, and I think you have earned America's gratitude," Mr Blumenthal said.

Dr Ford silently mouthed, "thank you".

She cried again when Democratic Senator Cory Booker of New Jersey called her "heroic".

During a break, GOP Senator Orrin Hatch told reporters that Dr Ford was "an attractive, good witness" but that it was too early to make a judgment. "I don't think she's uncredible."

An aide said on Twitter that the senator meant to describe her personality, not her appearance.

Senator Hatch said he still expects the Judiciary panel to vote on Mr Kavanaugh on Friday and expects him to be voted out favourably.

Questioning of Dr Ford proceeded in five-minute chunks. Other than committee chairman Chuck Grassley, the committee's Republicans stayed mum, each instead having Arizona sex-crimes prosecutor Rachel Mitchell ask questions during his allotted minutes. The 11 Republicans on the committee are all men.

Ms Mitchell's questioning presented a stark contrast to the sweeping statements of support from Democrats. Ms Mitchell spent most of her time trying to clarify details of Dr Ford's story, covering the night of the alleged assault and the professor's decision to come forward by confidentially telling her congressional representative and the Washington Post.

Mr Kavanaugh's prepared statement said he doesn't question that Dr Ford may have been sexually assaulted by someone, but strongly denied that he was the attacker.

"I categorically and unequivocally deny the allegation against me by Dr Ford," Mr Kavanaugh said. "I have never done that to her or anyone. I am innocent of this charge."

Dr Ford said that though they went to different high schools, she had been friendly with a classmate of Mr Kavanaugh's and attended a number of parties that the future judge also attended.

She said the attack occurred after she went upstairs to use the bathroom. She said she was pushed into a bedroom and onto a bed and that Mr Kavanaugh got on top of her. Mr Judge was in the room and encouraged the attack, she said.

"I believed he was going to rape me," Dr Ford said.

Mr Kavanaugh put his hand on her mouth to keep her from screaming, she said, and because it was hard for her to breathe, "I thought that Brett was accidentally going to kill me."

She said Mr Judge, who has denied any part in such an attack, jumped on them and she was able to escape.

Asked what she remembers from that night, Dr Ford responded: "The stairwell, the living room, the bedroom, the bed on the right side of the room as you walk into the room - there was a bed to the right - the bathroom in close proximity, the laughter - the uproarious laughter - and the multiple attempts to escape and the final ability to do so."

Under questioning from Ms Mitchell, Dr Ford said she didn't know how she got home that night. She said the party took place "somewhere between" her home and the Columbia Country Club, about seven miles away.

The Washington Post previously reported she told the paper the party took place near the country club.

"Has anyone come forward to say to you, 'Hey, remember, I was the one that drove you home'?" Ms Mitchell asked.

"No," Dr Ford responded. She said she didn't have her driver's licence at the time.

'I WANT TO APOLOGISE'

In opening the hearing, Mr Grassley said, "I want to apologise to you both for the way you've been treated," referring to threats made against Dr Ford and Mr Kavanaugh after her allegation became public.

As she prepared to leave, he thanked her "for your bravery coming out and trying to answer our questions as best you could remember".

Democratic Senator Dianne Feinstein of California thanked Ford for her "strength and bravery in coming forward."

"This is not a trial for Dr Ford," Ms Feinstein said. "It's a job interview for Judge Kavanaugh."

Ms Feinstein noted that two other accusers came forward in the last several days. They aren't scheduled to testify before the committee.

A second woman, Ms Deborah Ramirez of Colorado, claims Mr Kavanaugh exposed himself to her at a drunken party when they were freshmen at Yale University. And in the most lurid allegation yet, Ms Julie Swetnick of Washington said in a sworn statement released on Wednesday that Mr Kavanaugh took part in efforts during high school to get girls intoxicated so that a group of boys could have sex with them.

Republicans are trying to get Mr Kavanaugh, 53, confirmed as early as next week. Majority Leader Mitch McConnell of Kentucky has been preparing colleagues for a weekend session that would allow a final vote in a matter of days.

Republicans hold a 51-49 advantage in the Senate and can't afford more than one defection to ensure confirmation without Democratic support.

Several GOP lawmakers who remain publicly undecided - most notably Alaska's Lisa Murkowski, Maine's Susan Collins and Arizona's Jeff Flake - said they wanted to hear what Dr Ford has to say before making up their minds.

Capitol police imposed strict security measures to keep protesters at bay after about 70 people were arrested each day during Mr Kavanaugh's earlier hearing. At Dr Ford's request, the hearing was held in a smaller room with less space for media and the public, and protesters were being kept off that floor of the office building.