Updated 10.10pm

The second most-powerful Republican in the US Senate, John Cornyn, on Friday said the chamber would meet on Saturday at noon to vote on a procedural motion on the nomination of Brett Kavanaugh to the Supreme Court.

The Senate will vote on a motion to proceed, one of the steps leading to a full chamber vote on the nomination itself.

The Republican-led Senate Judiciary Committee on Friday voted to send the nomination of President Donald Trump's US Supreme Court pick Brett Kavanaugh to the full Senate for consideration, with one hold-out Republican calling for an FBI probe into sexual assault allegations against the nominee before a final vote is held.

The panel moved the federal judge's nomination to the full Senate on a party-line vote of 11-10, with all Republicans in support, and all Democrats opposed.

The concerns expressed by Republican Senator Jeff Flake could imperil the nomination if an FBI investigation is not launched.

CNN reported that Cornyn also said the FBI background investigation into Kavanaugh, which Republican Jeff Flake and other senators are seeking, would not last more than a week. The final vote to confirm Kavanaugh would come after the investigation.

Angry Democrats walked out as a Republican-led Senate panel set a vote over their objections.

The committee, with tempers flaring on both sides, met the morning after a jarring and emotional hearing into sexual misconduct allegations against Kavanaugh that gripped the country, with a university professor named Christine Blasey Ford accusing him of sexual misconduct. He denied the accusation.

As the committee, with 11 Republicans and 10 Democrats, set its vote for 1.30pm, some Democrats left the room in protest. "What a railroad job," Democratic Senator Mazie Hirono said.

A committee vote to approve Kavanaugh would pave the way for a final debate and vote on the Senate floor in the coming days, perhaps as early as Tuesday.

Republican committee Chairman Chuck Grassley said he found the testimony from both Ford and Kavanaugh "credible," but added, "There's simply no reason to deny Judge Kavanaugh a seat on the Supreme Court on the basis of evidence presented to us."

The timing of the panel's session gave committee members little time to review Thursday's extraordinary testimony from Kavanaugh and Ford, who accused him of sexually assaulting her when they were high school students in 1982.

Kavanaugh forcefully denied the accusations and accused Democrats of a "calculated and orchestrated political hit."

Senator Dianne Feinstein, the committee's senior Democrat, called Kavanaugh's remarks unseemly for a judicial nominee.

"This was someone who was aggressive and belligerent. I have never seen someone who wants to be elevated to the highest court in the country behave in that manner. In stark contrast, the person who testified yesterday and demonstrated a balanced temperament was Dr Ford," Feinstein said.

Another Democrat, Amy Klobuchar, noted that Grassley had thanked Ford for her bravery but nevertheless failed to back any further investigation.

"Where is the bravery in this room?" Klobuchar asked.

'THEY DON'T MATTER'

Flake, who had previously raised concerns about the allegations against Kavanaugh, said Ford gave "compelling testimony" but Kavanaugh provided "a persuasive response."

Soon after Flake made his announcement, he was confronted in an elevator while on his way to the committee meeting by two protesters who said they were sexual assault survivors.

"That's what you're telling all women in America - that they don't matter, they should just keep it to themselves," one of the protesters shouted at Flake in an exchange aired by CNN.

"I need to go to my hearing. I've issued my statement," Flake said.

The controversy has unfolded just weeks ahead of the November 6 congressional elections in which Democrats are trying to seize control of Congress from the Republicans.

If confirmed, Kavanaugh would consolidate conservative control of the nation's highest court and advance Trump's broad effort to shift the American judiciary to the right.

Democrats said Kavanaugh's confirmation could taint the Supreme Court, which prides itself on staying above the political fray.

"Voting to advance and ultimately confirm Judge Kavanaugh while he is under this dark cloud of suspicion will forever change the Senate and our nation's high court. It will politicise the US Supreme Court," Democratic Senator Patrick Leahy said.

Republicans hold a slim Senate 51-49 majority, making the votes of two other so-far undecided Republican moderates crucial: Lisa Murkowski and Susan Collins.

Joe Donnelly, a moderate Democrat who last year voted for Trump's previous Supreme Court nominee Neil Gorsuch, announced he would vote against Kavanaugh.

Democrats have urged a delay in the confirmation process to allow for an FBI investigation. The American Bar Association, which earlier endorsed Kavanaugh, and the dean of Yale Law School, which Kavanaugh attended, also called for an FBI probe, the first indication of the legal profession turning on the nominee.

Kavanaugh could be the deciding vote on contentious legal issues if he is confirmed to the nine-member court, with disputes involving abortion, immigration, gay rights, voting rights and transgender troops possibly heading to the court soon.

The court begins its next term on Monday, down one justice after the retirement of conservative Anthony Kennedy effective in July. Trump nominated Kavanaugh to replace Kennedy.

Ford testified on Thursday she was "100 per cent certain" Kavanaugh assaulted her in 1982. Kavanaugh said he was innocent and the victim of "grotesque and obvious character assassination."

Questions were raised about Kavanaugh's temperament at the hearing as well as his fiery political accusations and how that could impact his role on the court.

"I believe once he gets to the Supreme Court, he will call the balls and strikes fairly," White House adviser Kellyanne Conway told "CBS This Morning," using a baseball analogy.

Attention to the hearing moved far beyond the world of Washington politics. Ford has emerged in the eyes of many American women as a compelling figure in the #MeToo movement against sexual harassment and assault.