Donald Trump on Thursday brought things to a boil on both the international and domestic fronts, prompting Republicans to reckon with the unique dangers posed by the reckless president they’ve spent nearly two years enabling. At home, Trump stirred chaos by suddenly announcing in a meeting with G.O.P leadership that he would not sign a budget deal unless it included funding for his border wall, making a government shutdown a near certainty. Abroad, he stoked geopolitical fears by effectively forcing the resignation of Defense Secretary James Mattis, the last of the so-called “adults in the room” keeping watch over Trump, who abruptly announced Thursday he will quit in protest of the administration’s warm posture toward countries like China and Russia, and its hostile stance toward long-standing American allies.

It was a stunning, chaotic day in Washington, and perhaps the clearest sign yet that Trump is chewing through his leash. That prospect appeared to make Republicans, including some who have supported him, both frustrated and uneasy. Mitch McConnell and Paul Ryan, the two top Republicans on Capitol Hill, had reportedly attempted to “soothe” Trump into funding the government, attempting to convince him that money for his long-promised border wall was a “fight for another day.” But that approach proved unsuccessful, taking a number in his own party by surprise. “Did he just say that?” Senator Susan Collins said Thursday after reporters told her of Trump’s threat to blow up the deal. “Ugh, are you ruining my life?”

Things only got more chaotic after Mattis, who along with outgoing Chief of Staff John Kelly and former National Security Adviser H.R. McMaster, was part of a cadre of administration officials who supposedly protected the nation and the world from Trump’s worst impulses, announced his resignation in a fiery rebuke of the president’s policies toward Russia and other authoritarian actors. Senator Ben Sasse, a Republican on the Armed Services committee who has at times been critical of Trump, said in a statement it was a “sad day for America because Secretary Mattis was giving advice the President needs to hear.” Even McConnell, who has previously run cover for Trump, wrote in an unusually harsh statement that he was “distressed that [Mattis] is resigning due to sharp differences with the President on these and other key aspects of America’s global leadership,” and called on Trump to “recognize that nations like Russia” are foes, not friends.

“I urge [Trump] to select a leader who shares Secretary Mattis’s understanding of these vital principles,” McConnell wrote.

But Trump seems disinclined to do so. When other administration officials have been cast away, they have almost invariably been replaced by someone whose views are far more aligned with those of the president. And with Trump seeming increasingly backed into a corner, he seems even more preoccupied with finding loyalists. The irony, of course, is that the chaos he’s sowing—which has caused the markets to plunge and sparked significant geopolitical fears—could actually lead Republicans to finally turn on him at a crucial juncture. “Once Republican lawmakers start rebuking the president publicly like this over policy, it makes it easier for them to say: ‘It’s not just Mueller or ethics. There are other concerns,’” a former Trump aide told Axios on Friday. “Then it’s a slippery slope.”

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