Under most circumstances, the federal indictment of individuals in the orbit of the president of the United States would be a stunning development, but because the current president is Donald Trump—a man whose lawlessness nobody even bothers to dispute—we are far less surprised by the criminal activity itself than we are alarmed by crisis Trump might provoke in response.

Under most circumstances, the revelation would generate speculation about who would be arrested, and on what charges. Most speculation this weekend turned on the financial crimes of Trump’s former campaign manager, Paul Manafort, and that speculation turned out to be spot on. In Trump’s case, though, we were additionally left to wonder whether he will fire Justice Department special prosecutor Robert Mueller, or issue mass, blanket pardons to potential conspirators, or whether someone leaked the existence of the sealed indictment to stop Trump before he could perpetrate a modern Saturday Night Massacre.

For days leading up to Friday’s indictment news, the Trump White House, his allies in Congress, and their agents in the conservative media had—in an almost embarrassingly transparent fashion—been fabricating a pseudo-scandal, with the aim of turning Mueller’s investigation on its head, and creating a pretext for Trump to fire him.

Did Trump world get wind of the Manafort indictment? Was its hapless effort to invert the Russia scandal a clumsy response to inside knowledge? It is not alarmist to believe that Trump might’ve terminated Mueller this weekend had the existence of the indictment not become public, and stripped any scheme to end the investigation of its window dressing.

We don’t know. But we shouldn’t have to wonder, either. It is within the power of Republicans who claim to have reached their limits with Trump to make sure the worst never comes to pass. Trump and these Republicans are engaged in a silent standoff that will end in their permanent disgrace if, after maintaining silence, Trump fires Mueller, and the GOP Congress lets him get away with it.

The thought that the president might fire as many DOJ officials as possible to quash a criminal investigation of himself and his family and his advisers should be the furthest thing from anyone’s mind, and it should be a foregone conclusion that a president who went that route anyhow would find his presidency imperiled. But the Trump-GOP alliance has mooted both of these presumptions of responsible conduct. We have been on the precipice of a rule-of-law breakdown since Trump fired FBI Director James Comey to obstruct the FBI’s Russia investigation, and Republicans in Congress did nothing. In July, we learned Trump had pondered pardoning himself, his family, and his associates, for campaign crimes, and around the same time Trump publicly outlined criteria under which he would fire Mueller. Republicans in Congress again did nothing. If anything, in the months since then, most Republicans in Congress have become more permissive of Trump’s misconduct, not less. In August, they forgave his public alliance with murderous white supremacists in Charlottesville, VA, and the baseless pardon he gave disgraced former Maricopa County, AZ Sheriff Joe Arpaio simply for being Trump’s political ally and fellow racist. They have turned a blind eye to his erratic nuclear ‘diplomacy,” and his demonstrable lies about fellow members of Congress. When a lonely senator publicly acknowledged his unfitness for office, and the risk he poses to global peace, House Speaker Paul Ryan wrote it off as a Twitter spat, and urged everyone to focus on tax cuts instead.

Three months ago, most organs of the American right understood that firing Mueller would be a disaster, and tried to discourage Trump from doing anything rash—even if they didn’t go so far as to say firing Mueller should carry consequences. Today, Fox News (the president’s closest adviser) is a non-stop infomercial, hawking the idea of firing Mueller, and Ryan’s allies at the Wall Street Journal editorial board are openly encouraging an end to his investigation.

This is crazy even for Fox. Shut down Mueller probe and arrest Hillary. pic.twitter.com/0XMwdNJi0z

— Josh Marshall (@joshtpm) October 29, 2017

The pressure on Trump to fire Mueller has never been greater, but at the same time, the theoretical means by which Trump could be restrained have never been clearer.

As noted here last week, the three Republican senators in open defiance of Trump have the potential to place real limits on what Trump might dare do—but only if they are the faces of something more than a Potemkin rebellion.

Sens. John McCain (R-AZ), Bob Corker (R-TN), and Jeff Flake (R-AZ) can’t remove Trump from office, but they could jointly and credibly spell out consequences they’d impose were Trump to kill the Russia investigation.

They could pledge that if Trump fires Mueller, they will stop all legislation from passing until Congress reinstates Mueller. They could pledge that if Trump issues pardons for crimes his campaign committed, they will use similar leverage to insist upon an impeachment inquiry, complete with full public disclosure of any information Mueller has unearthed about them.

By saying nothing, they tempt Trump with the belief that Republicans in Congress will let him get away with anything. No doubt he believes that already, and with good reason. In theory, these senators can wait until Trump acts on his impulses and then impose the consequences anyhow, but having failed to establish the disincentive in advance, the temptation to do the easy thing, let bygones be bygones if Trump acts first, will be enormous.

The stakes here extend far beyond the question of whether the president can place himself and his favored allies above the law. Right now, the Mueller investigation is the only procedural response to Russia’s interference in the 2016 election with the power to discourage further hacking and other sabotage. If the American government’s response to the subversion of a national election is for the president to disband the law enforcement response, and for Congress to tacitly assent, bad actors will receive the intended message: Anything illegal they do to empower Trump politically will be forgiven. The damage to what’s left of U.S. democracy would be potentially lethal. But nearly the entire conservative movement has made peace with that, and the rare exceptions are declining to comment.

By not firing Mueller last summer, Trump hardened a conventional wisdom that the Russia investigation would be safe. Not only does that conventional wisdom underrate the likelihood that Mueller simply hadn’t gotten close enough for Trump to fire him, it underrates the possibility that Trump has already tried to fire Mueller, only to be deterred internally. The voices of deterrence are cracking, and Mueller isn’t backing off.

This article has been updated.