Judiciary Committee Chairman Lindsey Graham said the Democratic boycott was "their choice, adding, "We're not going to allow them to take over the committee."
"This is a groundbreaking moment" for conservatives, Graham said before the vote began.
Barrett, a federal appeals court judge whose confirmation would expand the top US judicial body's conservative majority to 6-3, was poised to win the 22-member committee's approval with unified support among its 12 Republican members even with the Democrats vowing to stay away.
In announcing their boycott of Thursday's vote, Senate Democratic leader Chuck Schumer and Judiciary Committee Democrats said of Barrett's nomination: "This has been a sham process from the beginning."
They added that they "will not grant this process any further legitimacy by participating" in the committee's vote just 12 days before the US presidential election between Trump and Democrat Joe Biden in which tens of millions of ballots have already been cast.
Trump nominated Barrett to succeed the late liberal Justice Ruth Bader Ginsburg. She is the Republican president's third Supreme Court nominee as he moves it further to the right.
A favorite of Christian conservatives, Barrett frustrated Judiciary Committee Democrats during her confirmation hearing last week by sidestepping questions on abortion, presidential powers, climate change, voting rights, Obamacare and other issues.
The 48-year-old Barrett is a devout Catholic who personally opposes abortion. Barrett told the committee last week that she believed the landmark 1973 Roe v. Wade ruling legalizing abortion nationwide was not a "super-precedent" that could never potentially be overturned. Barrett also said she had "no agenda" to roll back abortion rights. Trump said in 2016 he would appoint justices who would overturn Roe.
PUSH TO CONFIRM BEFORE ELECTION
Senate Republicans, who have made confirmation of Trump's conservative judicial appointees a high priority, have pulled out all the stops to ensure that the chamber can confirm Barrett to the post before Election Day on Nov. 3, as the president has requested. Republicans hold a 53-47 Senate majority, making her confirmation a virtual certainty.
Trump has said he believes the Supreme Court will decide the election's outcome and has made clear that he wants Barrett on the bench for any election-related cases.
Democrats pressed her to recuse herself from such cases because of a conflict of interest in potentially deciding the political fate of the president who nominated her so close to the election. She rebuffed their pleas.
No nominee to the Supreme Court has ever been confirmed by the Senate this close to a presidential election.
Republicans are hoping that Barrett's confirmation can give an election boost to incumbent senators in the party facing tough re-election fights, including Graham in South Carolina and panel members Joni Ernst in Iowa and Thom Tillis in North Carolina.
Democrats were incensed that Senate Republicans moved forward with the nomination so near an election after refusing in 2016 to allow the chamber to act on a Supreme Court nomination by Trump's Democratic predecessor, Barack Obama, because it was an election year.
Some on the left have floated the idea of expanding the number of justices if Biden wins to counter the court's rightward drift in light of the actions of Senate Republicans in 2016 and now. Republicans have decried the idea as "court-packing."
Biden said last week he was "not a fan" of court-packing but has kept his options open. The number of justices has been fixed by law at nine for more than a century.
Trump appointed Barrett to the Chicago-based 7th US Circuit Court of Appeals in 2017. If confirmed, Barrett could serve on the Supreme Court for decades, alongside Trump's two other appointees, Neil Gorsuch and Brett Kavanaugh.
This story has been published from a wire agency feed without modifications to the text.
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