When reporters asked Trump Monday if he would fire the special counsel, he responded ominously, “We’ll see what happens.”

It's not the first time this president has put out a trial balloon about firing the man charged with investigating him. Recognizing the growing threat to Mueller's job security, a group of four senators (two Democrats and two Republicans) have merged bills to protect the special counsel from presidential retaliation, though It's unclear how likely such a bill is to become law. And, as they have before, some Republicans are publicly warning the president that firing Mueller would amount, as Senate Judiciary Chairman Chuck Grassley put it, to "suicide" for Trump.

For some context on just how bad things are at this moment compared to October 1973—when an embattled Richard Nixon went on his own firing spree in hopes of scuttling the Watergate probe—I called up my favorite legal scholar, Noah Feldman. The historian and Harvard Law professor is usually pretty measured in assessing Trump's presidency, but he said some things that genuinely frightened me.

VICE: How do you think where we are now, historically speaking, compares to October of 1973?

Noah Feldman: It feels pretty different to me in terms of mood. There was emerging at that point, I think, some clarity to the effect that there had been a crime and there seemed to be increasing evidence of a cover-up. Here, we know there was serious Russian effort to influence the election—because there have been indictments on that from Mueller’s team. We know there are crimes associated with that. But the idea that there has been a cover-up directed from within the White House is, at this point, still very much in the realm of speculation. It may be that Mueller’s team has evidence of that, but if so they’re holding it pretty close to the vest.

Is your understanding that the president is correct in asserting that he has the power to fire the special counsel?

Technically speaking, the president would have to first repeal the regulation that is in place in the Department of Justice [governing Mueller's job]. Now, it is within the president’s power to direct the acting attorney general for this purpose—Rod Rosenstein—to rescind the regulation, and then [Trump] could direct him to fire Mueller.

That's because we have no evidence there's just cause to remove Mueller?

Correct, and the regulation requires cause. But the president could direct the Department of Justice to rescind the regulation. And at that point, Mueller is just an employee of the Department of Justice and the president has the authority to fire him. So there’s an intervening step that has to take place. So when Trump says, "I believe I can do this," we don’t have to take him literally to mean he can do it without rescinding the regulation. But what he’s saying is through that route, he has the legal authority to do it.

If Rosenstein refuses to play ball in this scenario, is the idea that the president would remove him and find someone who would repeal that regulation?

Yeah, that's the Saturday Night Massacre model. I predict Rosenstein would refuse to remove the regulation.

"Worst-case scenario for him is he fires Mueller and he fails to fire him, and Mueller is like, 'I'm not fired.'"

Then it would go to the solicitor general, also a Republican—I'm not going to ask you to speculate about who would do the president's bidding...

Someone in the building will do it at some point. Not every DOJ employee will quit. You could also imagine a scenario where Trump really would screw himself up: Trump could just try to do it himself. Just announce, "I have withdrawn the regulation and I hereby fire him." At that point Mueller will get on TV and say, "I am still in office, he has failed to fire me legally, the regulation has not been followed, he lacked the authority to fire me," and there we would have a genuine constitutional crisis over the question of like: Has he been fired? That would be a real crisis because there would be two competing views about what the Constitution demands under these circumstance. That may have to go to court or some other mechanism and under those circumstances Trump will have made it way worse for himself. Worst-case scenario for him is he fires Mueller and he fails to fire him, and Mueller is like, "I'm not fired." That could actually happen, frankly.

OK, so let's say Trump does decide to go nuclear. What do you think that actually looks like in practice? How do the key players and institutions respond?

Everyone will immediately draw an analogy to the Saturday Night Massacre, and then the $54,000 question is how will the Republican congressmen and senators react? Let’s assume this is all happening before the midterms, so we have the Republican House and Republican Senate. If Republican House members move to impeach, then the game will change very drastically and that will put also a lot of pressure on Republican senators. That would really be remarkable, transformational change.

If we don’t see that movement immediately, if they act like ordinary politicians and hold their cards close to their vests, then Democrats will probably find themselves screaming and yelling for impeachment using the parallel of the Saturday Night Massacre. And then Republicans will do a gut check and make a choice: Will they move in that direction—worried that they’ll be harmed in the midterms—or will they tough it out and think it’ll actually help them in the midterms that the Democrats are calling for impeachment? Right now the conventional wisdom is that talk of impeachment is bad for the Democrats and good for the Republicans. The question is would a firing of the Saturday Night type move the goalpost and change that? That’s a big gamble for Trump to take but it’s conceivable that he would take it. And if he did, what we would have to find out pretty darn quickly is what do the Republican House and Senate think? What would the Wall Street Journal editorial page say? We know what the New York Times editorial page will say. It will say, “Impeach.” But will the Journal editorial page say, “Well, we should impeach but not convict.” What will Fox News say?

If there is a coordinated effort to protect the president and the Republican House decides not to impeach, we will just be in a new world where all the Democratic yelling about impeachment in the world won’t have made a difference. And I have to say, I believe that is a possible scenario.

How could Mueller respond himself, short of a lawsuit or some kind of legal action?

Mueller has signaled [there may be] a report on obstruction of justice. That strongly suggests his team has a document ready to go right now. What I think would probably happen is that if Mueller were fired, the Mueller team report on obstruction would immediately emerge. And my guess is that actually includes a further paragraph they've prepared in advance that says the firing of Comey was obstruction and the firing of Mueller will be definitive proof of obstruction. I think there will be some way that the Mueller team will have an exploding mechanism.

One question is, we always talk about firing Mueller, [but] will he fire the whole team? if he fires Mueller and the whole team, then they can release this report in their private capacities somehow. If he fires just Mueller, whoever's Mueller's number two can immediately release this and can go public and can say, "The president has obstructed justice not just with Comey but with firing Mueller." And then so then our whole conversation is going to turn to: Is the president obstructing justice in firing Mueller?

Leaving aside Congress, what do you think would go on inside the law enforcement apparatus of the country if Trump did go nuclear like this?

The only thing I could imagine would be mass resignations. And I think a lot of people would not mass resign and be urged not to, because you don't want the whole Justice Department to shut down.

There are two tools. There's the legal tool, which is resignation, and then there would be like a shelter-in-place tool, where they would do a slowdown, or refuse to do the business of government, or sign letters. Or you could [see] like, walkouts at the Department of Justice, where DOJ employees in white shirts and ties could march silently to the White House, stand there, turn around, and march back.

Does it matter if it appears Trump is spurred to do this by his own attorney being searched?

That would make it far worse in terms of it looking like obstruction of justice. In fact you could make the argument that Mueller knew exactly what he was doing and that by making this about the president's lawyer, he really personalized it in such a way that if Trump fires him, he can go on television and be like, "I was fired for one reason and one reason only, namely that I was getting too close to the president, and therefore it's obstruction of justice to fire me."

Who has the power to check Trump if he goes this route?

Honestly, other than executive branch officials who can just resign, it's down to Congress. The only other option would be the judiciary, and they would only come into the picture if Trump fails to cross his t's and dot his i's. Short of that, the honest truth is the framers set up a system that depends on the separation of powers. If the president abuses his power, in the end, the popular check comes from the House and the Senate. If that breaks, then it's just a terrible design flaw in the Constitution, and a serious challenge to the legitimacy of our constitutional structure as capable of sustaining the rule of law.

This interview has been lightly edited and condensed for clarity.