WASHINGTON — When Justice Ruth Bader Ginsburg was released from the hospital last weekend after another in a string of health scares, blue America breathed a sigh of relief. Only one more month, many whispered, until the start of a presidential election year when filling a vacancy on the Supreme Court would be off limits in the Senate.
But would it?
That was the case in 2016 when Senate Republicans stonewalled President Barack Obama’s nomination of Judge Merrick B. Garland to fill an opening that occurred with 11 months left in Mr. Obama’s tenure. “Let the people decide,” was the Republican mantra at the time, as they argued that it was improper to consider Mr. Obama’s nominee when voters were only months away from electing a new president who should get the opportunity to make his or her own choice on a Supreme Court justice.
But with the tables turned and Republicans holding the White House, that almost certainly would not be their refrain in 2020 if a court seat were to open up through death or retirement.
Senator Mitch McConnell, the Kentucky Republican, majority leader and unapologetic mastermind of the 2016 Garland blockade, has made clear that he would move ahead with a high court nominee from President Trump. The only potential barrier would be resistance from his own party on the grounds it would be hypocritical and unfair for Republicans to do what they prevented Democrats from doing four years ago.
Widespread defections on that basis seem highly unlikely.
And Senator Susan Collins, the moderate Republican from Maine who broke with her party and backed holding a confirmation hearing and vote on Judge Garland in 2016, said she would take the same position in 2020: Should a vacancy arise, the sitting president should get the chance to choose a nominee, and the Senate should move forward to confirm.
“My standard on the nomination of Supreme Court nominees remains the same,” she said. “As long as the president is in office, he has the constitutional right to nominate. I thought that Merrick Garland should have had a hearing and a vote. Now obviously, senators could have voted against him based on the timing. But to block the nomination from proceeding at all, I thought was wrong.”
Senator Charles E. Grassley, Republican of Iowa, chaired the Judiciary Committee but refused to convene a hearing for Judge Garland and met with him only grudgingly. As a result, he said last year that he would not consider a nominee in 2020 if he were still chairman of the panel. But he has since left the top spot on the panel to take over the Finance Committee, sparing him the prospect of either going back on his word or infuriating Mr. Trump and his colleagues. Allies say they doubt he would take a stand against a nominee since he is no longer chairman.
Republicans say the difference between 2016 and 2020 is one of political alignment. Democrats held the White House and Republicans controlled the Senate in 2016; Republicans now control both. To Mr. McConnell and his colleagues, that shift justifies their new position. But in 2016, Republicans focused most of their argument against taking up Mr. Obama’s nominee not on party control, but on the basis of the approaching presidential election, and they would face thunderous charges of hypocrisy if they took up a nomination next year.
Democrats remain angry over the treatment of both Mr. Obama and Judge Garland and expect Republicans to move aggressively if the chance arose for Mr. Trump to place a third nominee on the court. Should any nominee replace one of the four justices picked by Democratic presidents, it would cement a commanding 6-3 conservative majority on the high court, and the lure of that lineup would probably prove irresistible to Republicans.
“Do you have any Republican senator saying that in 2020 we won’t ram through a Supreme Court nominee?” asked Senator Chris Coons, Democrat of Delaware and a member of the Judiciary Committee. “Of course they will.”
Mr. Coons, an active player on judicial nominations, called the stonewalling of Judge Garland — a man some Republicans had earlier said they would consider a strong choice by a Democratic president — “among the worst things the Republicans have done in my decade in the Senate.” His colleagues agree. The dispute, which colored both the confirmation fights over Justices Neil M. Gorsuch and Brett M. Kavanaugh, has badly frayed relationships both on the committee and in the Senate.
Should Republicans remain united, however, there is little Democrats could do to impede a nomination, because a series of rules changes has neutered the filibuster when it comes to judicial picks, meaning the majority party can push through the president’s choice without a single vote from the minority.
Though Democrats would lack procedural weapons, they and their allies say they would still mount a challenge using whatever tools available, and their attention would focus intently on the nominee. While it is hard to imagine proceedings more toxic than the Kavanaugh hearings, a move to install an election-year nominee with the specter of impeachment swirling in the capital would certainly be considered inflammatory by Democrats and those on the left.
“Any scenario where an impeached president is trying to jam through a Supreme Court pick in an election year, in direct defiance of the precedent Mitch McConnell set with Merrick Garland in 2016, would rightly spark a war,” said Brian Fallon, the head of Demand Justice, a progressive group formed in response to the Republican blockade of Judge Garland.
Mr. Coons said his preference would be that the conflict be avoided altogether and no vacancy arose. If one did, the fight would no doubt spill over into the presidential and congressional elections. It could also give momentum to calls by some Democratic presidential contenders and advocacy groups to reconfigure the court to offset what they see as an illegitimate conservative imbalance — building support for ideas that have not yet been embraced by the party mainstream.
“While there are few options we would have to stop that nominee before the election, my hope is it would mobilize Democrats at the polls to insist on restoring balance to the court,” Mr. Coons said.
One wild card is the timing of any vacancy. Judge Garland was nominated to replace Antonin Scalia, who died in mid-February, a time frame that would ordinarily be well beyond the period needed to pick a nominee for Senate review and a confirmation vote if it had not been for the Republican refusal to take up the nomination. A vacancy that occurred later in 2020, much closer to the election, could present Republicans with a tougher argument to make, though there would no doubt be intense pressure for them to move forward no matter what the calendar said.
But with no vacancy imminent — and Democrats holding their breath that none will occur — just one thing is certain about a potential 2020 Supreme Court fight: It would be brutal for all involved.