Senate Democrats have a lot of reasons to reject Neil Gorsuch, President Trump’s first Supreme Court nominee.

He is a down-the-line conservative. He was appointed to a federal appeals court by George W. Bush, wrote a book arguing that judges should embrace an absolute right-to-life principle in assisted suicide cases, and has backed religious challenges to the Affordable Care Act (including in the Hobby Lobby case). He sided with corporations and against workers in a variety of cases, including one in which a Kansas State professor was fired for requesting more leave after a cancer diagnosis, and one involving a truck driver who was fired for abandoning his malfunctioning truck after waiting in a freezing, unheated cabin for three hours.

There’s more: Gorsuch was nominated to the Supreme Court by President Donald Trump, who has attacked the federal judiciary repeatedly, and whose actions — restricting immigration from some Muslim countries, cracking down on undocumented immigrants, and rolling back environmental regulation — are certain to draw legal challenge after legal challenge. Some of those challenges will almost certainly come before the Supreme Court.

If that weren’t enough, Gorsuch is nominated for the same seat that Merrick Garland was, and Senate Republicans’ refusal to so much as hold hearings for Garland still, understandably, enrages Senate Democrats, who feel the seat was stolen.

Democrats are essentially helpless to stop many of Trump’s decisions. But not this one: Senate Democrats have the ability to block Gorsuch from joining the Court by filibustering. Unless Republicans can peel off eight Democrats to break that filibuster, Gorsuch won’t be able to join the Court.

And yet the conventional wisdom in Washington is that Gorsuch — whose confirmation hearings began Monday and are schedule to end Thursday — is a sure thing, and will coast to a confirmation vote without much controversy. Politico's Burgess Everett reports that Democrats are weighing a deal that would see Gorsuch confirmed in exchange for "a commitment from Republicans not to kill the filibuster for a subsequent vacancy during President Donald Trump’s term."

How such a promise could be made binding, I don't know. But even without that promise there’s a strategic story Democrats can tell themselves about why letting Gorsuch slide would be a good idea. Whether or not that story makes any sense is a good question.

The big unknown: when do Democrats want Republicans to go nuclear?

The biggest reason Democrats might want to go easy on Gorsuch is that Senate Majority Leader Mitch McConnell really does have a way to force the nomination through. He can change the filibuster rule so that it only takes 51 votes, not 60, to invoke cloture on a Supreme Court nominee, just as Senate Democrats did for non-Supreme Court judicial nominees and all executive nominees in November 2013.

The precedent has been set for that change, and Republican senators like Mike Lee and Lamar Alexander have been calling for it since Republicans recaptured the Senate in early 2015. McConnell himself has signaled that if Democrats filibuster Gorsuch, he’s willing to go nuclear, telling reporters, “Gorsuch will be confirmed; I just can't tell you exactly how that will happen, yet.”

This presents a dilemma for Democrats. If the nuclear option is invoked, that doesn’t just confirm Gorsuch. It means that if a liberal or swing justice dies or retires while Republicans have a Senate majority, giving Trump the power to truly reshape the Court, there will be nothing they can do to stop him. The 5-4 majority that has upheld reproductive rights, struck down same-sex marriage bans, and generally prevented total conservative domination of the nation’s highest court would be replaced by a permanent conservative majority.

Without the filibuster, Republicans could confirm a replacement with a simple majority. They could put in someone like 11th Circuit Judge Bill Pryor, who has called Roe v. Wade “the worst abomination in the history of constitutional law,” and Democrats would not be able to block him.

So when it comes to Gorsuch, two scenarios could play out for Democrats:

Full obstruction: Democrats filibuster Gorsuch. McConnell invokes the nuclear option. Unless enough Republicans oppose the rule change, Gorsuch is confirmed. Republicans keep or gain Senate seats in 2018. Then a liberal justice or swing vote retires or dies. Trump nominates someone conservative (a crony, a hard-right ideologue, or a mainstream pick with little paper trail) to replace them. Democrats have no way to stop Trump from replacing a liberal or moderate vote with a conservative one: With a 51-vote threshold for nominees, most nominees have a good shot at getting confirmed.

Strategic surrender: Democrats decline to filibuster Gorsuch, allowing at least eight members of the caucus to vote for cloture. Then they save their ammunition for the (hypothetical) next fight: filibustering anyone whom Trump picks to replace Anthony Kennedy, Ruth Bader Ginsburg, or Stephen Breyer, the three oldest justices. Because of the higher ideological stakes for the Court, this strategy bets that less conservative Senate Republicans such as Lisa Murkowski, Rob Portman, Cory Gardner, or Susan Collins might be less willing to go nuclear — forcing Trump to moderate his choices.

How Democrats will figure out which of these strategies would work best

The reasoning behind strategic surrender is at least somewhat compelling. But whether or not it makes sense depends on a number of factors:

Are there Republicans who’d vote for a conservative replacement to Ruth Bader Ginsburg, but not go nuclear for them? This is the big variable. Suppose Ginsburg dies or retires in the next four years and Trump nominates Bill Pryor or another hard-line conservative to replace her. If three or more less conservative Republicans come out against the nomination entirely, then it doesn’t really matter whether the threshold to confirm them is 60 votes or 51. If the filibuster were destroyed by the Gorsuch fight, then the nomination would just fail normally in an up-or-down vote.

Strategic surrender then only makes sense if you think Gardner, Portman, Murkowski, or Collins would vote for a nominee like that in an up-or-down vote, but wouldn’t go so far as to change the rules of the Senate to put them on the Court.

How long could you keep up blocking a conservative replacement? Let’s say Trump nominates a Gorsuch clone — a hard conservative who says the right things and charms senators and doesn’t seem like an ideologue — for Ginsburg’s seat. And a sufficient number of Republicans oppose going nuclear that Democrats successfully block the pick. Now let’s suppose the nomination just sits there for months and months.

At some point, do the anti-nuclear Republicans break and come around to the nuclear option? Or does Trump fold first, pull the nominee, and pick someone more moderate? If you think the latter is likely, then surrender on Gorsuch makes sense. If you think the former is more likely, then it doesn’t.

How likely do you think Republicans successfully going nuclear over Gorsuch is? If you doubt that less far-right GOPers like Collins or Murkowski are willing to blow up Senate rules for someone who almost certainly would vote to overturn Roe v. Wade, then full obstruction starts to make more sense. If the nuclear option isn’t possible in this case, then Democrats really can prevent Gorsuch from taking his seat indefinitely.

Is it important to punish Republicans for obstructing Merrick Garland? I hate to say this, but I’m afraid it’s time for some game theory. In the 1980s, the game theorists Anatol Rapoport and Robert Axelrod found that if you play the famous prisoner's dilemma game (where cooperation helps both parties but they face strong incentives to defect) again and again, one of the best strategies you can use is "tit for tat": do whatever your opponent did the last time.

As political scientist Seth Masket points out, in the case of the Supreme Court, this implies that Democrats should respond to the obstruction of Garland by obstructing Gorsuch. In the long run, tit for tat produces more cooperation than the alternatives, and showing Republicans that Democrats won't tolerate that kind of obstruction could have some long-term benefits for the party.

Will there even be a next fight? Maybe Kennedy, Ginsburg, and Breyer are all still on the court in four to eight years when Trump leaves office — or maybe Democrats retake the US Senate in 2018 (despite a very tough map) or 2020, before any of the justices retires or dies. In those cases, all of this is moot. What happens to Gorsuch and the filibuster rule won’t affect the “next fight” at all, because Democrats will be able to either nominate a liberal justice or use a Senate majority to block conservative ones.

The fact of the matter is that Trump is going to get a lot of judges Democrats don’t like on courts

The answers to those questions depend a lot on probabilities that are inherently impossible to know with any certainty. Will Murkowski kill the filibuster for Scalia’s replacement, but not Ginsburg’s? Will she keep not killing the filibuster for Ginsburg’s replacement month after month? Can the nuclear option succeed for Gorsuch? Will blocking Gorsuch to punish Republican obstruction of Garland change Republicans’ behavior and make them more cooperative going forward?

But the basic fact of the matter is that replacing Antonin Scalia is Donald Trump’s job, as infuriating as that is for Democrats after the Garland situation. And if Ruth Bader Ginsburg passes away or Anthony Kennedy retires or Elena Kagan decides to quit and sail around the world, Trump will be able to name a replacement too, with much greater consequences for the Court.

Democrats are trying to figure out how best to play a set of very bad cards. They can do everything they can to keep Collins, Murkowski, and Gardner equivocating. But ultimately, it’s the least conservative Republicans in the Senate (people who are by no means moderate) who will decide if Gorsuch and a hypothetical conservative replacement to Ginsburg or Kennedy go through.

Democrats can try to affect their thinking, but their tools are limited.

Unless Democrats overcome a very tough Senate map in 2018 to regain a majority, the fact of the matter is that Republicans, on their own, can use the nuclear option to confirm anyone they want for the Supreme Court for the next four years. And that will almost certainly mean the Court moves to the right.