President Trump is scheduled to announce his nominee for the vacant US Supreme Court seat this week. There should be no illusions about the confirmation battle that will follow.

No matter what Senate Minority Leader Chuck Schumer says about revenge not being a motive for Democrats or how fair they plan to be, there’s only one way the Republicans will be able to replace the late Justice Antonin Scalia.

It’s nuclear or nothing.

The so-called nuclear option would happen if Republicans fully quash the filibuster, a process Democrats began eroding in 2013 when they nuked the filibuster for most judicial and executive-branch nominees.

The Democrats had the majority then, and heedless of the possibility that the tables might soon be turned, former leader Harry Reid decided to short-circuit the ability of the minority to frustrate the will of President Obama by forcing Democrats to get 60 votes on nominees.

The Democrats used the shift to pack the lower courts with Obama nominees. But, as Schumer now admits ruefully, that gives Republicans an edge now that they control Congress and the White House. It means that no matter how much Democrats rail against Trump’s cabinet choices, every single one of them is likely to be confirmed.

However, Reid left one exception when he altered the rules: the Supreme Court. So while Republican Senate Majority Leader Mitch McConnell might abhor trashing tradition, he might have no choice but to use his power to end the filibuster altogether.

Unless he can persuade eight Democrats to back Trump’s SCOTUS nominee while keeping all 52 Republicans in line, McConnell will have to go nuclear.

McConnell’s decision to not even consider Obama’s choice of Judge Merrick Garland to replace Scalia after the justice’s death last February was a high-stakes gamble that paid off.

It’s true that there was no precedent for asking a Senate controlled by the opposition to alter the court’s 5-4 split by replacing a conservative with a liberal (even the New York Times noted Garland was to the left of two of the current liberals on the court) in an election year. But once it fell to Trump to fill the seat, Democrats were going to go all-out to prevent him from preserving a conservative majority on the court for the foreseeable future.

But this is about more than revenge. The left’s horror over Trump had made an already highly partisan environment on Capitol Hill even more toxic. With their base not even waiting for Trump to do anything before taking to the streets, Democrats will dig in against the GOP on even the most trivial of matters. When it comes to the future of American law and polarizing issues like abortion, they are certain to fight to the last ditch.

Given the large number of red-state Democrats up for re-election in 2018, there is a chance McConnell will be able to split the opposition and win without a rules change. But that possibility is limited by the certainty that some defecting Democrats would then face primary challenges from the increasingly belligerent Bernie Sanders wing of the party that seeks to recreate the same dynamic on the left that the Tea Party had on the GOP.

Schumer is likely to have the votes to filibuster any Trump SCOTUS nominee no matter how qualified or mainstream his or her views might be. That leaves McConnell with only a nuclear strike on the last vestige of the filibuster as his only path to a court confirmation.

The filibuster was probably finished no matter which side won in November. It’s arguable that the Republicans would have used it to stop any Hillary Clinton court nomination had Trump lost. Given the stakes involved in replacing Scalia and the disappearance of any neutral ground left between the two parties, for either side to meekly allow their opponents to shift the court without a battle to the death has become unimaginable.

The end of the requirement for a filibuster-beating supermajority is the only way the court is ever going to get back to nine.