A deeply torn US Senate is set to confirm Amy Coney Barrett to the Supreme Court, Republicans overpowering Democratic opposition and institutional norms to secure President Donald Trump’s nominee the week before election day.

Ms Barrett’s confirmation on Monday was hardly in doubt as Senate Republicans seized the opportunity to install a third Trump justice, securing a conservative court majority for the foreseeable future.

With no real power to stop the vote, Democrats argued into the night Sunday that the winner of the November 3 election should be the one to choose the nominee to fill the vacancy left by the late Justice Ruth Bader Ginsburg.

The 48-year-old appellate judge’s rise opens up a potential new era of rulings on abortion, gay marriage and the Affordable Care Act.

A case against the Obama-era health law is scheduled to be heard on November 10.

Senate Majority Leader Mitch McConnell scoffed at the “apocalyptic” warnings from critics that the judicial branch was becoming mired in partisan politics as he defended its transformation under his watch.

“This is something to be really proud of and feel good about,” the Republican leader said on Sunday during a rare weekend session.

Mr McConnell said that, unlike legislative actions that can be undone by new presidents or politicians, “they won’t be able to do much about this for a long time to come”.

Vice President Mike Pence would typically preside over Monday’s vote, but after a close aide and others on his staff tested positive for the coronavirus, it was unclear whether he would attend.

He is scheduled to hold a campaign rally in Minnesota, arriving back in Washington ahead of the expected evening vote.

But Democratic leaders are asking him to stay away, saying in a letter to Mr Pence that it is “not a risk worth taking”, according to a copy obtained by The Associated Press.

“Nothing about your presence in the Senate tomorrow can be considered essential,” the Democrats wrote, warning of the risk not just to senators but the police, restaurant workers and others who keep the Capitol running.

Senate Democratic leader Chuck Schumer of New York said the Trump administration’s drive to install Ms Barrett during the coronavirus crisis shows “the Republican Party is willing to ignore the pandemic in order to rush this nominee forward”.

To underscore the potential health risks, Mr Schumer urged his colleagues not to linger in the chamber but “cast your votes quickly and from a safe distance”.

Some Republican senators tested positive for the coronavirus following a Rose Garden event with Mr Trump to announce Ms Barrett’s nomination, but they have since said they have been cleared by their doctors from quarantine.

The confirmation was expected to be the first of a Supreme Court nominee so close to a presidential election.

It is also one of the first high court nominees in recent memory receiving no support from the minority party, a pivot from not long ago when a president’s picks often won wide support.

Ms Barrett presented herself in public evidence before the Senate Judiciary Committee as a neutral arbiter and at one point suggested, “It’s not the law of Amy”.

But her writings against abortion and a ruling on “Obamacare” show a deeply conservative thinker.

She was expected to be seated quickly on the high court.

“She’s a conservative woman who embraces her faith.

“She’s unabashedly pro-life but she’s not going to apply ‘the law of Amy’ to all of us,” the Judiciary Committee chairman, Republican Senator Lindsey Graham said on Fox News.

At the start of Mr Trump’s presidency, Mr McConnell engineered a Senate rules change to allow confirmation by a majority of the 100 senators, rather than the 60-vote threshold traditionally needed to advance high court nominees over objections.

It was escalation of a rules change Democrats put in place to advance other court and administrative nominees under President Barack Obama.

On Sunday, the Senate voted 51-48 vote to begin to bring the process to a vote by launching the final 30 hours of Senate debate.

Two Republicans, Lisa Murkowski of Alaska and Susan Collins of Maine, voted against advancing the nominee, and all Democrats who voted were opposed.

California Senator Kamala Harris, the vice presidential nominee, missed the vote while campaigning in Michigan.

Monday’s final tally was expected to grow by one after Ms Murkowski announced her support for the nominee, even as she decried filling the seat in the midst of a heated race for the White House.

Ms Murkowski said on Saturday she would vote against the procedural steps, but ultimately join Republican colleagues in confirming Ms Barrett.

“While I oppose the process that has led us to this point, I do not hold it against her,” Ms Murkowski said.