Democratic hopeful Joe Biden urged lawmakers to wait until after November's election to tackle a Supreme Court vacancy that President Donald Trump has pledged to fill quickly, as the nomination becomes a new flashpoint in the battle for the White House.
The prospect of an expedited Senate confirmation vote in the weeks before the election has sparked furious pushback from Democrats desperate to stop Trump moving the court lastingly to the right.
Two Republican senators have also registered their opposition to any rushed vote to replace Ruth Bader Ginsburg, the popular liberal justice who died Friday at 87.
Biden, speaking Sunday in Philadelphia, accused Trump of exercising "raw political power" by attempting to "ram" through his court choice amidst a bitterly fought election campaign.
"Even if President Trump wants to put forward a name now, the Senate should not act on it until after the American people select their next president and the next Congress," said Biden, who himself spent 36 years in the upper chamber.
"If Donald Trump wins the election, then the Senate should move on his selection -- and weigh that nominee fairly. But if I win the election, President Trump's nomination should be withdrawn."
The president said Saturday that he expected to announce his nominee in the coming week and that it "will be a woman -- a very talented, very brilliant woman."
Biden urged a handful of wavering Republican senators to "follow your conscience."
The timing of a Senate vote, before the election or in the lame-duck session immediately afterward, remains unclear.
Lisa Murkowski of Alaska said no vote should take place before the election, and Susan Collins of Maine asserted that the choice should be left to whoever is elected in November.
With Republicans holding 53 of the 100 Senate seats, Democrats face an uphill battle in blocking a Trump nominee.
Either way, politicians in both parties are bracing for a seismic battle in a year that has already seen an impeachment vote, the Covid-19 pandemic and a bruising economic collapse.
'Arrows in our quiver'
Among the Democrats' few options: delaying tactics in the Senate and efforts to mobilise public pressure on more moderate Republicans to split with their party.
"We have our options... arrows in our quiver," House speaker Nancy Pelosi, a senior Democrat, said Sunday on ABC's "This Week."
She offered few details but ruled out the possibility of a government shutdown.
The court vacancy has provided a welcome new theme for Trump, who has struggled to play down the toll of the coronavirus pandemic, now fast nearing the grim total of 200,000 deaths.
Pelosi seemed intent on keeping the virus issue front and center, returning to that theme repeatedly during her ABC interview, just as Biden emphasised it in his speech.
'Confirm before Election Day'
Democrats are decrying what they say is the hypocrisy of Republicans -- particularly Senate leader Mitch McConnell -- who in 2016 blocked Barack Obama's attempt, much earlier in that election year, to fill another Supreme Court vacancy.
But Republicans now insist that the situation this year is different, with the same party controlling both the Senate and White House.
"The right thing is for the Senate to confirm before Election Day," Republican Senator Ted Cruz told ABC.
Both parties see the balance of the court -- as it rules on vexed issues including abortion, healthcare, gun control and LGBTQ rights, as of utmost importance.
Conservatives now control five of the nine court seats, but Chief Justice John Roberts sometimes sides with liberals.
If confirmed quickly enough, a new conservative justice would be part of a 6-3 majority, and could play a crucial role, in their first months on the court, if the November election faces legal challenges.
Cruz, who was on a Trump list of potential court nominees, insisted Sunday that a full court was needed to avoid a critical deadlock should a battle over the election outcome reach the Supreme Court.
"An equally divided 4-4 court can't decide anything," Cruz said. "We need a full court on Election Day."
Media reports say Trump is focused on two potential justices: Amy Coney Barrett, a 48-year-old federal appeals court judge based in Chicago, and Barbara Lagoa, 52, a federal judge from Miami.
Of the score of names on a tentative list released earlier by Trump, Barrett, a fervently anti-abortion Catholic -- is considered among the most conservative.
Analysts said Lagoa, as a Cuban-American, could help Trump win votes in the key state of Florida.
No date has been set for Ginsburg's funeral or a public memorial service, sure to be a major national event.