CHRISTINE Blasey Ford, the woman who has accused supreme court nominee Brett Kavanaugh of sexual assault, has said she is “100%” certain he was her attacker.

The California psychology professor testified Kavanaugh sexually assaulted her as he and a friend shared “uproarious laughter” in a locked room at a 1980s high school gathering.

READ MORE: Speaking out about sex crimes rarely leads to justice

Ford recounted her allegations to the Senate Judiciary Committee and a riveted nation in a drama that threatens to derail Kavanaugh’s Supreme Court nomination.

When top committee Democrat, California Senator Dianne Feinstein asked Ford how she could be sure Kavanaugh was the alleged attacker, Ford said: “The same way I’m sure I’m talking to you right now.”

She said she was terrified to come forward but did so because she felt it was her civic duty.

The 51-year-old’s account, delivered in a soft and sometimes-halting voice, came as the judiciary panel began an extraordinary session that Republicans hope will let them salvage Kavanaugh’s chances of joining the high court.

The conservative jurist’s Senate confirmation had seemed assured until Ford came forward and then other women emerged with additional allegations of sexual misconduct.

Kavanaugh, now 53, denied them all and said his family and his name “have been totally and permanently destroyed”.

He said his confirmation process has become “a national disgrace” and a “character assassination”.

President Donald Trump nominated Kavanaugh for the vacancy on the Supreme Court, the body that has the final word on key issues like abortion and same-sex marriage.

In an election-season battle that is being waged along a polarised nation’s political and cultural fault lines, Trump and most Republicans have rallied behind Kavanaugh.

They have accused Ford and the other women of making unproven allegations and have questioned why they had not publicly revealed them for decades.

But Trump, who fiercely defends his nominee, said he would be watching and was “open to changing my mind”.

Ford has said Kavanaugh trapped her on a bed and tried undressing her, grinding his body against her and muffling her cries with her hand. “I believed he was going to rape me,” she said in her opening statement.

Democrats have rallied strongly behind Ford.

Asked by Patrick Leahy, of Vermont, for her strongest memory of the alleged incident, Ford mentioned the two boys’ “laughter – the uproarious laughter between the two and they’re having fun at my expense”.

The professor spoke carefully and deliberately during the hearing, using scientific terminology at one point to describe how a brain might remember details of events decades later.

The boys’ laughter was “indelible in the hippocampus”, she said.

Ford has said Kavanaugh’s friend Mark Judge was also in the room.

Judge has said he does not remember the alleged incident and has declined to appear before the panel.

Ford told the top committee Democrat, California Senator Dianne Feinstein, that she had “agonised daily” over coming forward about the alleged decades-old attack.

She said she feared the personal consequences would be akin to “jumping in front of a train”.

Kavanaugh said part of the reason for the allegations is anger by some about Trump and the 2016 US presidential election, and out of revenge on “behalf of the Clintons”.

In the 1990s, Kavanaugh was part of the team that investigated President Bill Clinton as part of special prosecutor Kenneth Starr’s investigation.

The report led to Clinton’s impeachment process, though he was not removed from office.

Kavanaugh and Fordwere the only witnesses invited to give evidence.