Protesters gather in front of the Supreme Court on Capitol Hill in Washington. The Senate Judiciary Committee is scheduled to hear from Supreme Court nominee Brett Kavanaugh and Christine Blasey Ford, the woman who says he sexually assaulted her. Picture: Patrick Semansky/AP

Washington - A woman who has accused Brett Kavanaugh, President Donald Trump's Supreme Court nominee, of sexually assaulting her will testify at a high-stakes Senate hearing on Thursday that could determine whether he will be confirmed to the lifetime job after a pitched battle between Republicans and Democrats.

The hearing, which has riveted Americans and intensified the political polarization in the United States, occurs against the backdrop of the #MeToo movement against sexual harassment and assault.

Christine Blasey Ford, a university professor, and Kavanaugh, a conservative federal appeals court judge picked by Trump in July for a lifetime job on the high court, are the only two witnesses scheduled for the Judiciary Committee.

Ford, who has yet to speak or appear publicly, will give her account of an alleged incident in which she has said Kavanaugh sexually assaulted her in 1982 at a gathering of teenagers in Maryland when both of them were in high school.

President Donald Trump's Supreme Court nominee, Brett Kavanaugh testifies before the Senate Judiciary Committee on Capitol Hill. File picture: Alex Brandon/AP

Kavanaugh has denied the allegations by Ford and two other women who have come forward.

A line began to form outside the Senate office building where the hearing is due to begin at 10 a.m. (1400 GMT).

The all-male Republican majority on the Senate Judiciary Committee has hired a female lawyer with experience prosecuting sex crimes, Rachel Mitchell, to question Ford. Democratic senators are set to ask their own questions.

"My motivation in coming forward was to provide the facts about how Mr Kavanaugh's actions have damaged my life so that you can take that into serious consideration as you make your decision about how to proceed," Ford said in prepared testimony to the committee.

'TELL THE TRUTH'

"It is not my responsibility to determine whether Mr Kavanaugh deserves to sit on the Supreme Court. My responsibility is to tell the truth," she added, adding that she was "terrified" to testify but that she considered it her "civic duty" to relate the details of the incident.

In his prepared testimony, Kavanaugh again "unequivocally and categorically" denied her allegation, as well as "other false and uncorroborated accusations" by his other accusers.

"Sexual assault is horrific. It is morally wrong. It is illegal. It is contrary to my religious faith. And it contradicts the core promise of this nation that all people are created equal and entitled to be treated with dignity and respect," Kavanaugh said.

Ford, a psychology professor at Palo Alto University in California, has said a drunk Kavanaugh attacked her and tried to remove her clothing at a gathering of teenagers in Maryland when he was 17 years old and she was 15.

"Brett groped me and tried to take off my clothes. He had a hard time because he was so drunk and because I was wearing a one-piece bathing suit under my clothes. I believed he was going to rape me," Ford said, adding that Kavanaugh and a friend of his were "drunkenly laughing during the attack."

Supreme Court appointments must be confirmed by the Senate, and Trump's fellow Republicans control the chamber by a narrow 51-49 margin. That means that a handful of moderate Republican senators who have not announced whether or not they support Kavanaugh could determine his fate. Committee member Jeff Flake is among these.

The committee could vote on Kavanaugh's confirmation on Friday, with a final Senate vote early next week.

Some Democrats have called on Kavanaugh to withdraw in light of the allegations.

The controversy has unfolded just weeks ahead of the Nov. 6 congressional elections in which Democrats are trying to seize control of Congress from Trump's fellow Republicans. Kavanaugh's confirmation would cement conservative control of the high court as Trump moves to shift it and the broader federal judiciary to the right.

Two other women, Deborah Ramirez and Julie Swetnick, have also accused Kavanaugh of sexual misconduct in the 1980s.

Ramirez accused Kavanaugh of exposing himself during a drunken dormitory party during the 1983-84 academic year when both attended Yale University.

Swetnick, whose allegations emerged on Wednesday, said she witnessed efforts by Kavanaugh and others to get girls drunk at parties so that they could be raped. She also said Kavanaugh was present at a 1982 party at which she was raped.

Trump and some other Republicans described the allegations as part of a last-minute "smear" campaign, though the president indicated that he will be paying close attention to the hearing. "I can always be convinced," Trump said on Wednesday.

Swetnick, in an interview on MSNBC, said she had not planned to air her allegations one day before the hearing.

"Kavanaugh is going for a seat where he's going to have that seat on the Supreme Court for the rest of his life. And, if he's going to have that seat legitimately, all of these things should be investigated," Swetnick said.