With special counsel Robert Mueller facing a deafening drumbeat of criticism from conservatives in recent days, Democrats have grown increasingly worried — and some conservatives have grown hopeful — that President Donald Trump will fire him any day now.

Rep. Jackie Speier (D-CA) said there was a “rumor on the Hill” that Trump planned to fire Mueller at the end of this week. Meanwhile, conservative Rep. Matt Gaetz (R-FL) told my colleague Alex Ward recently that Mueller should have been fired “long ago.” Former Attorney General Eric Holder called for protests in the event of Mueller’s firing, and the liberal activist group MoveOn.org has set up a plan for rallies in case it happens.

Now, both Trump and his lawyers say they have no plans to fire Mueller. (The president reiterated that statement Sunday night.) But of course, it’s at least possible that this is a lie, or even that Trump could change his mind later on.

With four former Trump advisers already facing charges in Mueller’s investigation, and the probe apparently moving closer to Trump’s family members and potentially the president himself, the rationale for firing the special counsel might appear clear. And so long as Republicans control Congress, the prospect of Trump actually being impeached and removed from office for this is still a very long shot.

But it’s important to realize that there are also some real, practical reasons for Trump not to fire Mueller. That is: Doing so would cause him several new problems, without entirely solving his old ones.

For one, any attempt to fire Mueller would likely lead to a storm of leaks. For another, he’d have to fire more people than just Mueller to get rid of him. Trump would have to do yet more to actually end the investigation. Perhaps most importantly, the controversy that would ensue would make a Democratic takeover of Congress more likely — which could end up putting Trump and his administration under even more investigative scrutiny.

I of course can’t predict what the president will do in the future, particularly if the legal jeopardy for him and his family members grows more serious. (Though he’s still got that pardon power in his pocket...) But Trump has clearly been reluctant to move against Mueller so far — and that hesitation makes sense for these reasons.

1) Firing Mueller would unleash the leaks

When Trump fired FBI Director James Comey back in May, the eventual consequence was Mueller’s appointment. But it’s also worth remembering what happened in between those two events — namely, a remarkable series of bombshell leaks that made their way to the press.

The leaks were about events both old (Trump’s inappropriate request for Comey’s “loyalty” at a private meeting and his later request that Comey end the investigation into Michael Flynn) and new (Trump’s revelation of classified intelligence to Russian officials in an Oval Office meeting). And they continued after Mueller’s appointment, with the revelation that Jared Kushner sought a back channel to communicate with Russia during the transition.

The sources for these leaks varied. The fired Comey was the ultimate source of some of them, as he tried to get out information he had long sat on. Others were likely leaked by still-serving government officials alarmed by what they saw as a cover-up. And top reporters began digging on these topics even more vigorously after Comey’s firing. But the commonality is that an attempted cover-up unleashed leaks. (We saw a similar situation after Trump got a Justice Department warning that Michael Flynn could be vulnerable to Russian blackmail and failed to act on it — the warning leaked into the press weeks later.)

Now, when it comes to Mueller, keep in mind that he and his team have been at work for seven months, and the FBI investigation into Trump associates and Russia was ongoing for months before that. He’s gathered a ton of information in that time — from his two cooperating witnesses George Papadopoulos and Michael Flynn, from other people he’s interviewed, from intelligence intercepts, from various subpoenas, and so on. We recently learned that Mueller even obtained the full transition team email accounts of 13 Trump aides.

Basically, Mueller’s team has a lot. We don’t know how much of what they have relates to potential criminality, or how much might just be politically damaging were it to leak. But the gist is that we have reason to believe that any attempt by Trump to cover up or obstruct the investigation would be responded to with some painful leaks.

2) Trump would have to clear out much of the Justice Department, not just Mueller

The process that it would take to fire Mueller also makes it more difficult and costly to actually do it.

Mueller is a special counsel appointed under a Justice Department regulation that tries to make it deliberately difficult for him to be fired. The regulation states that only the attorney general can fire a special counsel, and that even then, there would have to be a good reason — that it could only be done for “misconduct, dereliction of duty, incapacity, conflict of interest, or for other good cause.”

In another twist here, Attorney General Jeff Sessions recused himself from the case — so it is Rod Rosenstein, the deputy attorney general who appointed Mueller in the first place, who has the sole authority to fire the special counsel.

Rosenstein repeated in congressional testimony last week that he believes he is the only person who has the authority to fire Mueller, that he believes he legally can’t fire Mueller without “good cause,” that he’s seen no good cause to fire Mueller yet, and that he would not carry out an order to fire Mueller without that good cause.

Now, most agree that Trump could probably get rid of Mueller if he really wanted to. He’d just have to fire Rosenstein, and anyone else in the Justice Department’s line of succession who’d refuse to carry out the order, until he finds someone willing to do it.

But the upshot is that we’re not talking about one firing here — we’re talking about several, to get rid of Mueller alone. The more people who go down, the uglier the move looks. And even then...

3) Firing Mueller wouldn’t necessarily end the investigation

The Mueller investigation is more than just Mueller. It predated him of course, and since his appointment, he’s assembled a team of more than a dozen prosecutors who are working with FBI agents. And a case against Paul Manafort and Rick Gates is currently moving toward a trial. This is a sprawling operation that can’t just be shut down by the firing of one person.

Jack Goldsmith, a Harvard law professor and former Justice Department official in the George W. Bush administration, made this point on Twitter recently. “The overall investigation has already yielded fruit and there is a clear justification for it to continue,” he tweeted. “Pressure in and out of DOJ to appoint Mueller’s successor, as opposed to killing investigation, would be enormous, as would pressure to appoint someone of integrity/independence who would continue pushing hard. FBI Dir. Wray would continue to investigate until ordered not to.”

Again, it would probably be possible for Trump to do this if he really wanted to — he could get whichever crony of his is left standing at the Justice Department to shut down the investigation, or appoint another crony to run it. But it’s another layer of difficulty and controversy that makes it harder to end the investigation entirely, and calls into questions the benefits of firing Mueller.

It’s also worth remembering that President Richard Nixon failed at this stage of the cover-up process. He fired his top Justice Department officials until he found one who’d get rid of the special prosecutor investigating Watergate. But then that Justice official (Robert Bork) appointed a new special prosecutor, Leon Jaworski, who ended up investigating the case vigorously.

4) A Trump cover-up could improve Democrats’ chances of retaking Congress — which would only worsen his legal woes

It’s well understood that Trump would face a political backlash for firing Mueller. In and of itself, that probably wouldn’t be enough to hold him back from doing it — after all, he’s been willing and even eager to make controversial political moves in the past.

But the real risk for Trump is in what that political backlash could lead to — a Democratic takeover of one or both chambers of Congress in 2018.

It’s not that Trump would necessarily care about his party’s electoral fate. The more serious problem is that Democratic control of even one chamber would unleash empowered opposition party–controlled investigations into him and his administration on Russia, obstruction, and a host of other issues.

That’s an underappreciated reason why firing Mueller might backfire for Trump — because if it helped Democrats retake Congress, Trump would end up under far more investigative scrutiny, not less.

Already, the national environment is worrying for Republicans. The president is unpopular. Democrats lead by 11 points in FiveThirtyEight’s average of congressional generic ballot polls. And Democrats have been consistently bettering their 2016 performance in special elections.

As of now, Trump has nearly a year to turn that around or at least improve things somewhat. Or he could spark an enormous crisis over the rule of law in America by firing Robert Mueller. We’ll see which he picks.