History teaches us that healthy democracies don’t turn into failed democracies overnight. Like a tree rotting from the roots, it’s a lengthy decay that only becomes fully visible when it is well advanced. And even at that late stage, parts of the tree can appear to be verdant and vigorous.

The healthy part of U.S. democracy was on display on Tuesday, when tens of millions of Americans defied the country’s shamelessly antiquated election infrastructure to register their votes. Although both parties emerged with things to cheer about, the biggest story of the election was the Democratic takeover of the House of Representatives. But even as votes were still being counted in some close races on Wednesday, there was another clear signal of the sickness that is eating away at the American system from the inside.

Officially, the rushed departure from the Justice Department of Attorney General Jeff Sessions was described as a “resignation.” Of course, it was really a firing. In fact, it was tantamount to a double firing. In appointing Sessions’s interim replacement, Matthew Whitaker, a conservative Republican lawyer who had been serving as Sessions’s chief of staff, President Trump passed over the Justice Department’s second-in-command, Rod Rosenstein, and also stripped Rosenstein of responsibility for overseeing the investigation being carried out by Robert Mueller, the special counsel.

In a statement released on Thursday, the Justice Department said, “The Acting Attorney General”—meaning Whitaker—“is in charge of all matters under the purview of the Department of Justice.” That includes the Russia investigation. Without actually firing Rosenstein, an independent figure who has been a strong defender of Mueller, Trump has accomplished the same thing that a dismissal would have brought about: the appointment of a more loyal, and perhaps more pliable, figure to oversee the final stages of Mueller’s work.

Everyone in Washington knows that Trump has been itching to fire Sessions since March of 2017, when the former Alabama senator recused himself from overseeing the Russia investigation. In July, 2017, Trump told the Times, “If he was going to recuse himself he should have told me before he took the job, and I would have picked someone else.” With the midterms safely out of the way, Trump contained himself no longer.

Unlike many of Trump’s appointees, Sessions hadn’t become enmeshed in ethical scandals, and he couldn’t be faulted for failing to support the President’s agenda. Under his leadership, as he pointed out in his forced resignation letter, the Justice Department helped beef up immigration enforcement, targeted transnational drug gangs, and “prosecuted the largest number of violent offenders and firearm defendants in our country’s history.” Session’s firing offense was to have failed to protect Trump adequately from the Russia investigation—a fact about which the President has made no secret.

To be clear, forcing out the Attorney General without any proper cause was a disgraceful departure from precedent. But in the scheme of things it was less of a threat to the rule of law than the sidelining of Rosenstein and the appointment of Whitaker, who is on record as having expressed concerns about the scope of the special counsel’s inquiries. That was the real banana-republic move, and its intent couldn’t have been clearer. “This is a frontal assault on the Mueller investigation,” Susan Hennessey, the executive editor of the Lawfare blog, wrote on Twitter. “Trump sees a window and he’s taking it.”

In an interview with CNN last year, before he joined the Administration, Whitaker raised concerns about reports that Mueller’s team was looking into the finances of the Trump Organization. “We cannot have unfettered prosecutors overturning every rock that [is] unrelated to any, like, nexus to the underlying issues, which is Russian coordination in the 2016 election,” he said. He also raised the possibility of Trump firing Sessions and appointing a replacement who “doesn’t fire Bob Mueller, but he just reduces his budget to so low that his investigation grinds to almost a halt.”

What is needed is a public assurance from Whitaker that he will leave the supervision of the Mueller investigation to Rosenstein, which is what a number of Democrats were asking for on Wednesday when they called on Whitaker to recuse himself from the matter. At the very least, Whitaker should immediately issue a statement pledging to uphold the independence of the Justice Department, to support Mueller, and to allow him to complete his inquiries unimpeded.

But there are grounds to doubt that such a statement would be believable or enforceable—one of which is that Whitaker was Trump’s pick, or at least Trump approved his appointment. It seems unlikely that the President did so without giving careful consideration to what Whitaker would do if he got the promotion.

On the plus side, some observers believe that the Mueller inquiry has already proceeded far enough that it would be difficult for anybody to sabotage it. “To ‘shut down’ the investigation at this point would require not just a face-off with Mr. Mueller but also with special agents in charge of multiple field offices with a vested interest in seeing their responsibilities through, and possibly even a battle with the F.B.I. director, Christopher Wray,” Asha Rangappa, a former F.B.I. counterintelligence agent, wrote in the Times last month. (Indeed, on Thursday morning, anonymous sources told CNN that Mueller’s team has already begun drafting its final report.)

Other legal experts take a far less reassuring view. A few weeks ago, in a piece about the role that Rosenstein has played in protecting Mueller, Hennessey and her Lawfare colleague Benjamin Wittes wrote, “What kind of mischief could be made by someone hostile to the Mueller probe and seeking to protect the president and his allies? The short answer is a whole lot.”

Although the special-counsel statute grants Mueller a good deal of independence, he is obliged to keep the Attorney General (or acting Attorney General) informed about major developments, such as decisions to bring criminal charges. As Hennessey and Wittes point out, the regulations say that the Attorney General “may after review conclude that the action is so inappropriate or unwarranted under established Departmental practices that it should not be pursued.” The Attorney General also has the authority to fire the special counsel “for cause,” and he can also help determine what happens to any concluding report that the special counsel files to the department. Conceivably, Whitaker could try to bury it.

So far, only a few Republicans have expressed disquiet about the firing of Sessions and the sidelining of Rosenstein. “I’m concerned Rod Rosenstein will no longer be overseeing the probe,” Senator Susan Collins wrote, on Twitter. “Special Counsel Mueller must be allowed to complete his work without interference—regardless of who is AG.” Senator Lamar Alexander also issued a statement, saying that Mueller must be allowed to complete his investigation, as did Mitt Romney, the former Republican Presidential candidate who is now the senator-elect from Utah.

This wasn’t nearly enough. The President does not care about precedent or the principle that everybody, including the occupant of the Oval Office, should be treated as equal under the law. If Republicans are serious about protecting Mueller, there is a simple way for them to show it. They can support a piece of legislation that would make it difficult, or impossible, for Trump or Whitaker to fire the special counsel. Earlier this year, the Senate Judiciary Committee advanced a bipartisan bill of this nature, but Mitch McConnell, the Majority Leader, prevented it from going any further. As recently as September, McConnell said that he believed Sessions “ought to stay exactly where he is.” Now Trump has axed Sessions and replaced him with a loyalist. On Wednesday, McConnell stayed conspicuously silent.