It drew the line under a bruising nomination process defined by harrowing testimony from a woman who says Kavanaugh tried to rape her when they were teenagers - and by his fiery rebuttal.

The two-vote margin of victory made it the closest Supreme Court confirmation vote since 1881 – and by far the most contentious since Clarence Thomas, the conservative justice accused of repeated sexual harassment by a former assistant, Anita Hill, in 1991.

As Chief Justice John Roberts swore in Kavanaugh during a private Supreme Court ceremony, protesters demonstrated loudly outside, at one point rushing the steps of the court and banging on its ornate bronze doors while some sat on a Lady Justice statue.

Donald Trump handed one of the biggest victories of his presidency

The confirmation means Trump has succeeded in having his two picks seated on the court – tilting it decidedly to the right in a major coup for the Republican leader less than halfway through his term.

During an evening rally in Topeka, Kansas, Trump was greeted by prolonged cheers on what he called a “truly historic night.”

Yale has many Brett Kavanaughs. One of them peed on my door

“I stand before you today on the heels of a tremendous victory for our nation, our people and our beloved Constitution,” he told supporters after signing Kavanaugh’s commission aboard Air Force One.

Senate Majority Leader Mitch McConnell, who has railed against Kavanaugh’s critics, said he was “proud” of his colleagues while Vice-President Mike Pence, who presided in the Senate during the vote, called it a “historic day for our country”.

It reflects a high water mark of the Trump presidency: Republican control of the White House, the Senate, the House of Representatives and the judiciary’s top court.

But the Kavanaugh spectacle, fuelled by extraordinary accusations and counterclaims in nationally televised hearings, and tense battles over an 11th-hour FBI investigation to address the assault allegations, has inflamed political passions.

Amy Schumer and Emily Ratajkowski among hundreds arrested after march in Washington against Brett Kavanaugh

Hours before the vote, scores of protesters broke through barricades and staged a raucous sit-in on the US Capitol steps.

As protesters chanted “Shame!” and “November is coming!” police took several dozen demonstrators down the steps and put them in plastic flex-cuffs.

With tensions simmering, Pence got an earful from activists who booed and chanted “Vote them out!” as he walked to his motorcade.

Kavanaugh’s confirmation process has laid bare the partisan gridlock on Capitol Hill and the political polarisation of America just a month before midterm elections.

“You don’t hand matches to an arsonist, and you don’t give power to an angry left-wing mob. That’s what they have become. The democrats have become too extreme and too dangerous to govern,” Trump said.

“Republicans are the party of law and order and justice. And we really have become even more so than ever before the party of opportunity and wealth.”

The only Republican senator to oppose Kavanaugh’s confirmation

Democratic senators, who had battled hard to block the 53-year-old judge, insisted the caustic battle over Kavanaugh would galvanise Democrats at the polls.

“It is a sad day, but the recourse will have to be on election day,” Democratic Senator Amy Klobuchar told reporters.

Kavanaugh’s confirmation had already been all but sealed Friday, when he won the support of key Senate Republican Susan Collins and conservative Democrat Joe Manchin.

The choice of Kavanaugh to replace retired justice Anthony Kennedy was controversial from the start – but the initial focus was solely on the conservative views held by the married father of two.

His ascent to the Supreme Court was thrown into doubt last week after university research psychologist Christine Blasey Ford testified that he had sexually assaulted her at a Washington area gathering in the early 1980s.

Trump aide Kellyanne Conway says she too is a victim of sexual assault

The brutal hearing sparked a supplemental FBI dive into Kavanaugh’s background and a weeklong delay of the Senate vote.

While many Republicans said they were satisfied with the FBI probe, Democrats and Blasey Ford’s lawyers called the investigation insufficient.

Kavanaugh’s nomination seals a conservative majority on the nine-seat High Court, possibly for decades to come.

Hundreds of protesters were arrested on Capitol Hill in the past week – including several dozen in the hours leading to the final vote.

Authorities took the rare step of putting up low metal fencing around the Capitol, keeping the public some distance from the building. But protesters overran the barricades and defiantly claimed the Capitol steps.

After the confirmation, activists gathered in their hundreds on the steps of the Supreme Court, chanting slogans and banging on its closed front doors.

Senator Lisa Murkowski, the only Republican to oppose Kavanaugh, said it was time for the Senate – and Americans – to “heal” after such a divisive few weeks.

She acknowledged the anguish of the protesters who interrupted the historic Senate vote, telling reporters afterward that “I was closing my eyes and praying. Praying for them, praying for us and praying for the country.”