For any would-be authoritarian strongman, a lesson of history is that you can't do it by yourself. To accumulate power and vanquish your opponents, you need powerful elements of the state—such as the police, the armed forces, senior politicians, and the judiciary—to go along with your designs, or at least to stand aside as you do as you will. In some cases, such as Weimar Germany and Vittorio Emmanuel III's Italy, many people in positions of influence were willing to support an authoritarian upstart because their commitment to democracy was weak or nonexistent to begin with. In other cases, such as Vladimir Putin's Russia and Recep Tayyip Erdoğan's Turkey, elected leaders exploited threats of terrorism and domestic chaos to justify the curtailment of political rights and the harassment of political opponents.

The United States is a much stronger democracy than any of these examples. Indeed, its system was specially designed to prevent the emergence of an all-powerful executive. But as I pointed out last week, in a post about the threat that Donald Trump represents, the big question is whether the safeguards that were built into the country’s political architecture will prove up to the challenge of reining in his illiberal tendencies. Some of the initial signs have been far from promising. Over the weekend, though, the forces of light and hope got an assist from an unlikely source: Trump himself.

On Friday evening, the Washington Post reported that the Central Intelligence Agency, in a secret assessment, had concluded that the Russian government sought to tilt last month’s election toward Trump. Trump’s transition team quickly responded with a statement disparaging the C.I.A. "These are the same people that said Saddam Hussein had weapons of mass destruction," the statement said, adding, "The election ended a long time ago…. It's now time to move on and 'Make America Great Again.’ ” In an interview with Fox News's Chris Wallace which was broadcast on Sunday, Trump expanded on this incendiary statement, saying "nobody knows" whether it was Russian hackers who targeted Democrats and calling the suggestion that the Russians were trying to help him win "ridiculous.”

Just like that, Trump made an enemy of the intelligence community. Many intelligence professionals had already been suspicious of him—because of his disregard for facts, and because of his embrace of the retired Lieutenant General Michael Flynn, the National Security Adviser designate, whom some people in Washington regard as a conspiracy theorist. But this latest episode was something far more direct and personal. Never before has a President or President-elect spoken so dismissively of the C.I.A.

In taking this tack, Trump also invited his political opponents to attack him where his Administration's grip on power will be weakest: in the U.S. Senate, where the Republicans will have a majority of just two seats. On Sunday, two Republican members of the Senate Armed Services Committee, John McCain and Lindsey Graham—both of whom have, at times, been critical of Trump—issued a joint statement with two Democratic members of the committee, Chuck Schumer and Jack Reed, that said, "Recent reports of Russian interference in our election should alarm every American.... Democrats and Republicans must work together, and across the jurisdictional lines of the Congress, to examine these recent incidents thoroughly and devise comprehensive solutions to deter and defend against further cyberattacks."

McCain also appeared on CBS's “Face the Nation,” where he was asked about Trump's attack on the C.I.A. “I don’t know what to make of it, because it’s clear the Russians interfered," he replied. "Whether they intended to interfere to the degree that they were trying to elect a certain candidate, I think that’s a subject of investigation. But facts are stubborn things. They did hack into this campaign.”

On Monday, Trump was still feeling the blowback, and his minders were busy trying to limit the damage. Appearing on “CBS This Morning,” Kellyanne Conway sidestepped the question of whether her boss accepts as fact that Russian hackers targeted U.S. political institutions and individuals, but declared that "absolutely, he trusts the intelligence community." Seeking to shift the goalposts, Conway also said, "We don't want foreign interference in our politics, but we also don't want politics to interfere with our intelligence. That is what is happening now."

Appearing at a press conference on Capitol Hill, Mitch McConnell, the Senate Majority leader, distanced himself from Trump. McConnell said he had "the highest confidence in the intelligence community, and especially the Central Intelligence Agency." He endorsed McCain's call for hearings on the Russian threat. And he added, "Let me just speak for myself: the Russians are not our friends. I think we ought to approach all of these issues on the assumption the Russians do not wish us well."

Trump, meanwhile, was back on Twitter on Monday morning. Like Conway, he sought to shift the conversation away from his intemperate response to the Washington Post report. "Can you imagine if the election results were the opposite and WE tried to play the Russia/CIA card. It would be called conspiracy theory!" Trump wrote. A bit later, he added, "Unless you catch ‘hackers’ in the act, it is very hard to determine who was doing the hacking. Why wasn't this brought up before election?"

Of course, it was brought up. On October 7th, a month before election day, the Office of the Director of National Intelligence and the Department of Homeland Security issued a joint statement that began, "The U.S. Intelligence Community (USIC) is confident that the Russian Government directed the recent compromises of e-mails from US persons and institutions, including from US political organizations."

Trump doesn't confine himself to reality—nothing new there. For once, though, he has been called on it, and there will be more repercussions. The confirmation prospects of Rex Tillerson, the chief executive of Exxon Mobil, whom Trump reportedly has settled on as his pick for Secretary of State, have been further complicated. Other nominees will also be affected: Democratic senators are sure to take their confirmation hearings as a chance to ask whether they agree with Trump's statements about the C.I.A. and Russia. And, while that's happening, the new Administration will find itself embroiled in hearings about the extent and impact of the Russian cyber attacks. Testifying at these hearings, senior intelligence and law-enforcement officials are likely to contradict Trump, or at least express views that diverge from his.

For anyone who had been hoping that the fabled "checks and balances" in the U.S. system wouldn't fail us, this is just the sort of thing we want to see happening. Of course, it doesn't mean the threat of democratic erosion has been beaten back—far from it—or that Trump won't ride through this squall. But the reaction to his latest hissy fit does suggest that he has made his first big misstep since the election. In the phrase often attributed to Talleyrand after Napoleon ordered the summary execution of the Duke of Enghien, Trump's attack on the C.I.A., and his refusal even to countenance the notion that Putin's hackers sought to help him out, was "worse than a crime—it was a blunder."