Of the four senators who had not publicly disclosed how they would vote on ending debate until Friday, Collins and Manchin were joined by the Arizona Republican Jeff Flake in voting yes.

Lisa Murkowski, Republican of Alaska, voted against moving forward and said she would not support Kavanaugh in the final vote. “I believe Brett Kavanaugh is a good man,” Murkowski told reporters. “It just may be, in my view, he’s not the right man for the court at this time.”

Flake also told reporters he would vote for Kavanaugh over the weekend “unless something big changes”.

Trump tweeted his glee at the result: “Very proud of the US Senate for voting “YES” to advance the nomination of Judge Brett Kavanaugh!”

The timing of the final vote – expected to begin Saturday afternoon – is up in the air. A hitch arose on Thursday when Montana Republican Steve Daines said he would not be in Washington on Saturday because his daughter is getting married in his home state.

If the count on Kavanaugh ends up being tight, that would force Republican leaders to keep the voting open for longer than expected, perhaps until late Saturday night or Sunday.

Lawmakers might vote differently on the climactic confirmation roll-call, but the announcements by Collins and Manchin effectively seal Kavanaugh’s approval.

Confirmation of the 53-year-old Kavanaugh to a lifetime appointment on the nation’s highest court would be a signature achievement for Trump – who has already seen one nominee, Neil Gorsuch, ascend to the bench – his conservative base and Senate Majority Leader Mitch McConnell.

The vote occurred a day after the Senate received a roughly 50-page FBI report on the sexual assault allegations, which Trump ordered only after wavering Republican senators forced him to do so.

Republicans said that the secret document – which described interviews agents conducted with 10 witnesses – failed to find anyone who could corroborate allegations by his two chief accusers, Christine Blasey Ford and Deborah Ramirez.

Democrats belittled the bureau’s findings, saying agents constrained by the White House had not reached out to numerous other people with potentially important information.

The vote also occurred against a backdrop of smouldering resentment by partisans on both sides. That fury was reflected openly by thousands of boisterous anti-Kavanaugh demonstrators who have been in the Capitol complex for days, confronting senators in office buildings and even reportedly near their homes.

On the Senate floor, lawmakers’ comments underscored the lingering bitterness.

“What left-wing groups and their Democratic allies have done to Judge Kavanaugh is nothing short of monstrous,” Senate Judiciary Committee Chairman Chuck Grassley said before the vote.

He accused Democrats of using destructive, unwarranted personal attacks on the nominee and even encouraging the protesters, saying, “They have encouraged mob rule.”

Senator Dianne Feinstein, the committee’s top Democrat, said Kavanaugh’s testimony at last week’s dramatic judiciary panel hearing should “worry us all”, citing “a hostility and belligerence that is unbecoming” of a Supreme Court nominee.

Senate Minority Leader Chuck Schumer called the fight “a sorry epilogue to the brazen theft of Justice Scalia’s seat”. That reflected Democrats’ lasting umbrage over Republicans’ 2016 refusal to even consider Merrick Garland, President Barack Obama’s nominee to replace the late Antonin Scalia.

When Trump nominated Kavanaugh in July, Democrats leapt to oppose him, saying that past statements and opinions showed he would be a threat to Roe v. Wade, the 1973 case that assured the right to abortion.

They said he also seemed ready to knock down Obama’s health care law and to rule for Trump if federal authorities investigating his 2016 campaign’s connections to Russia attempt to initiate legal action.

But that evolved into a late-summer spectacle after Ford accused Kavanaugh of trying to rape her at an alcohol-infused high school gathering in 1982, when she was 15 and he was 17. Two other women also emerged and accused him of other incidents of sexual misconduct. Kavanaugh has denied all the claims.

Under pressure from wavering Republicans, party leaders agreed to an extraordinary Senate Judiciary Committee hearing last week that mesmerised the nation as Ford nervously recounted her story and said she was “100 per cent” certain that Kavanaugh was her attacker.

A fuming Kavanaugh strode into the same packed hearing room that afternoon and said he, too, was “100 per cent” certain the incident had not occurred.

Kavanaugh, who currently sits on the US Court of Appeals for the District of Columbia Circuit and previously worked for the independent counsel’s office during the investigation of President Bill Clinton, described opposition to his nomination as “revenge on behalf of the Clintons” and warned that “what goes around comes around”.