The past week has revealed a new principle in American politics: As President Trump grows more unhinged, his allies in Congress grow evermore committed to his administration.

The new year began where the last one left off, with a spate of alarming outbursts and transgressions. There was the president’s social media brinksmanship with North Korean dictator Kim Jong-un about the size of his “nuclear button.” “Will someone from his depleted and food starved regime please inform him that I too have a Nuclear Button, but it is a much better & more powerful one than his, and my Button works!” Trump wrote on Twitter. Given high tensions between the United States and North Korea, it was a dangerous move that further inflamed the situation.

The public was just beginning to absorb the consequences of that rhetoric when Michael Wolff gave us a distressing glimpse into the Oval Office with Fire and Fury: Inside the Trump White House. It is the portrait of a White House dedicated to pacifying a plainly unqualified president with childlike demands for attention and praise. Wolff, a longtime business writer with a checkered relationship to the truth, is an unreliable narrator, and his claims should be taken with appropriate caution. Still, he paints a picture that fits what we already know about the president, whose ignorance, impulsiveness, and disordered thinking is present in speeches, press conferences, and interviews.

Soon after Wolff’s revelations, the New York Times detailed President Trump’s effort to stop Attorney General Jeff Sessions from recusing himself in the Justice Department’s investigation into potential “collusion” between the Trump campaign and the Russian government. Trump pressed his counsel, Donald McGahn, to lobby Sessions to intervene on his behalf, a choice that stems from Trump’s belief that Eric Holder had protected President Obama from legal scrutiny while he served as attorney general. Legal scholars believe Trump’s actions may constitute obstruction of justice, the offense that ensnared Richard Nixon during the Watergate scandal.

As if to confirm the suspicions about his capacities, President Trump spent Saturday morning bragging about his mental prowess. “Actually, throughout my life, my two greatest assets have been mental stability and being, like, really smart,” said the president, adding that “I think that would qualify as not smart, but genius….and a very stable genius at that!”

Here was Trump inaugurating his second year as president with behavior demonstrating how unfit he is for the job. And because Democrats are out of power in Congress, the responsibility for addressing this falls to Republicans, who reacted not with concern but with apologetics.

“I feel an obligation to help him where I can,” said Sen. Lindsey Graham on NBC’s Meet the Press. “I’ve enjoyed working with him. I don’t think he’s crazy. I think he’s had a very successful 2017. And I want to help him where I can. And we should all want him to be successful. He’s got a lot on his plate.”

Graham’s positive words for the president are a complete reversal from two years ago, when he described Trump as a “race-baiting, xenophobic, religious bigot.” And it was just this past summer when Graham blasted him for “dividing Americans.” In recent months, however, the South Carolina senator has become friendly, even obsequious toward the president. Another Trump critic, Sen. Bob Corker of Tennessee, also seemed to soften his stance toward the president in recent days. He joined Trump for a trip to his home state on Monday, and Politico reports that he’s begun to “mend fences” with the president. House Republicans, meanwhile, continue to run interference for Trump in the face of the FBI’s investigation into his campaign, in addition to taking steps to conclude the House’s own inquiry into the question of Russian involvement in the 2016 race.

What accounts for this allegiance?

The most obvious answer is simple partisanship: President Trump is the leader of the Republican Party, and as we approach midterm elections, even disgruntled Republicans have a reason to keep good relations with the White House.

The problem with this explanation is that Trump is brutally unpopular, and his antics have alienated voters across the political spectrum. Doug Jones’ victory this past month in the Alabama Senate race would not have been possible without a substantial decline in Republican turnout.

Some of that was disgust or exhaustion with the Republican nominee, Roy Moore, and some of it was similar feelings toward the president. In exit polls, Trump had an even split of approval and disapproval, a remarkable outcome in a state that backed him by a margin of 25 points. The rational play for worried Republicans would be to back away from the president. But they’ve done just the opposite.

Alternatively, it’s possible that Republicans are holding on, and digging in, with the hope of saving their policy agenda. The longer the investigations drag on, the more likely the administration is embroiled in a truly fatal scandal, thus scuttling Republican plans for 2018 and beyond.

Perhaps the best approach is to collapse the various explanations into one: Republicans are acting as partisans, and they are worried about the upcoming elections, but they are also wary of Trump’s supporters, and they hope to preserve their agenda by doing as much as they can to protect the president from any serious fallout. After ceding control of the Republican Party to Trump, and investing themselves in the success of his presidency, Republican lawmakers may be in too deep to extricate themselves.

None of this is exculpatory. The president of the United States is unfit for the job and perhaps unable to carry out its duties. And the GOP, at this stage, doesn’t want to do anything about it. Republicans aren’t just gambling with their prospects. They’re wagering the security and well-being of the country.