WASHINGTON - The death of a warrior of the law and the seemingly indomitable US Supreme Court Justice Ruth Bader Ginsburg on Friday at 87 after a long battle with cancer, has brought the core agenda of American conservatives within tantalising reach, deepening the stakes in the upcoming election.

The sudden vacancy she left is set to shift the balance of the nine-seat bench of the Supreme Court to the conservatives for decades to come.

US Supreme Court justices are appointed for life or until they retire.

President Donald Trump has an opportunity now, with a Republican-majority Senate, to ram through an appointment while still in office, or risk losing power and leaving the appointment to the Democrats.

Early on Saturday (Sept 19), in a Tweet addressed to the Republican party, he said: "We were put in this position of power and importance to make decisions for the people who so proudly elected us, the most important of which has long been considered to be the selection of United States Supreme Court Justices. We have this obligation, without delay!"

Appointing a new Justice now opens the door to reversing gains of liberals and progressives, in terms of women's rights, LGBTQ rights, gun control, and even as far back as the landmark 1973 Roe v Wade judgement which decriminalised abortion - which has been in the sights of conservatives ever since.

A 2016 Pew Research Centre poll found that 65 per cent of voters cited appointments to the Supreme Court as an important factor in their voting decision. Now the struggle over filling Ginsburg's position adds yet another dimension to the bitterness of America's political divide, less than 50 days to the Nov 3 election.

Reportedly just days before her death, Ginsburg dictated a statement to her granddaughter Clara Spera, saying "My most fervent wish is that I will not be replaced until a new president is installed.'"

But even as hundreds gathered spontaneously at the Supreme Court late on Friday night in Washington, Senate majority leader Mitch McConnell was signaling a rush to replace Ginsburg, asserting "President Trump's nominee will receive a vote on the floor of the United States Senate."

It was in stark contrast to his own statement in February 2016 when, also faced with a vacant seat on the Supreme Court bench following the death of Antonin Scalia, a leading conservative voice, Mr McConnell had said then: "The American people should have a voice in the selection of their next Supreme Court Justice. Therefore, this vacancy should not be filled until we have a new president."

Republicans successfully stalled the filling of the position, which deeply rankled Democrats. Then-President Barack Obama's Supreme Court nominee, Merrick Garland, did not even get a hearing from the Republican-controlled Senate.

In the end, President Trump made two appointments - both of conservatives - to the Supreme Court. The first was Justice Neil Gorsuch in early 2017; the second Justice Brett Kavanaugh in 2018 - who replaced retired Justice Anthony Kennedy.

The Supreme Court bench is, thus, already somewhat ideologically conservative; another conservative appointment will decisively tilt it. Making a third appointment would be an enduring legacy for President Trump.

The gap between the two parties over the Supreme Court, has meanwhile widened. In August 2019, Pew Research found that three-quarters of Republicans and Republican-leaning independents had a favorable opinion of the Supreme Court, compared with only about half (49 per cent) of Democrats and Democratic leaners. "The 26 percentage point difference between the two parties is among the widest it has been over the past two decades," Pew research said.

Not every Republican will necessarily go along with the President and Senator McConnell. But to have six Republican-appointed judges on the bench is such an opportunity that it is hard to imagine the party will pass it up.

And while it would be unusually fast to complete the entire confirmation process in less than 50 days, it is possible. Alternatively, the Senate could even continue with hearings and confirm what would be a lame duck appointment even if President Trump, and some sitting Senators, lose the election.

An additional spectre looms - of a Supreme Court tasked to rule on a disputed election result. In that regard the composition of the bench is even more critical in the short term, for President Trump who has explicitly questioned the integrity and credibility of the electoral process - seemingly to prepare the ground to dispute the result should he lose.

"Ginsburg's death creates new dynamics if there is an election-related dispute before the Court," said Five Thirty Eight, a political analysis website in a commentary.

"Whether the court is 5-3 (with Ginsburg's seat not filled) or 6-3 (with a Trump nominee seated), Democrats would need two votes from (Republican)-appointed justices to win a case. So if there is some kind of electoral dispute that gets to the court, that's bad news for Democrats. It raises the spectre of a 4-4 tie in a pivotal election-related case, a potential deadlock that could complicate knowing who won the presidential race."

"One of the most divisive elections in America history will now likely be even more tense and fraught," it added.