Since Monday, Democrats have been quizzing Ms Barrett – judge on the Chicago-based 7th US Circuit Court of Appeals – on a wide range of issues, including her stance on abortion, healthcare, voting rights and equal marriage.
Mr Trump’s decision to press ahead with installing Ms Barrett, 48, has not only outraged Democrats and sections of the wider electorate, but it also broke with a precedent set by Senate Republicans just four years ago, when they refused to vote on then-president Barack Obama’s pick to replace Antonin Scalia.
If Ms Barrett, a pro-life Catholic, is confirmed then it would solidify a right-leaning majority in the highest court in the land for a generation, which could have implications for some of America’s most important and fiercely contested laws – including reproductive rights.
And with Republicans commanding a majority in the upper chamber, it looks all but inevitable that Ms Barrett will be confirmed before millions of Americans head to the polls, in what has been described as the most important election in living memory.
During day 4 of proceedings on 15 October, the Senate judiciary committee confirmed a vote on Ms Barrett would take place on 22 October, after rejecting Democrats’ pleas to delay the process until after the election.
“She has been rushed in a way that is historically unprecedented,” Senator Richard Blumenthal (Connecticut) said of the decision.
“There’s never been a nomination in an election year after the month of July, and the purpose of doing it is simply to have a justice on the Supreme Court, as the President said, to decide the election, and to strike down the Affordable Care Act.”
But Republicans said they were within their rights to appoint a justice in an election year, citing the US constitution and “precedent”.
“The precedent is clear,” said Republican senator Ted Cruz (Texas). “If the president and Senate are of the same party, the Senate, in all but extraordinary circumstances, confirms that nominee.”
Is there anything Democrats can do to stop Ms Barrett being confirmed?
When RBG died, President Trump waited just one day to announce that he intended to replace her before the election. Hours later on 19 September, Senate majority leader Mitch McConnell confirmed that he would accept a nomination, essentially giving the president the green light to proceed with filling RBG’s vacated seat.
At that point, there were some murmurings on Capitol Hill that Mr Trump’s old foe, Mitt Romney (Utah), could scuptter the president’s plans to nominate a justice. But with perhaps one eye on shoring up votes in his own seat, Mr Romeney later fell into line.
Senators Lisa Murkowski (Alaksa) and Susan Collins (Maine) have said that they will vote against Ms Barrett. But Republicans have a majority of of 53-47 in the upper chamber, meaning Democrats are powerless to stop to nomination.
In response to what they see as a breaking of precedent, Democrats have threatened to add more seats to the court or impose term limits on serving justices, who can sometimes spend decades on the court.
With Mr Trump trailing his presidential challenger, Joe Biden by a significant margin in most major polls, there is a very real chance that Democrats could control both the Senate and Congress next year.
If this proves to be the case, then Democrats could press ahead with packing the supreme court by sending a bill through both houses. Ms Barrett’s confirmation to the court would result in a majority of 6-3 in favour of conservatives. Democrats would seek to rebalance the ideological make-up of the court.