Donald Trump's administration was always going to end up in ashes.

The man elected president last November is a singularly corrupt and avaricious figure who was and is comically unsuited for the job, and vesting in him the powers of the presidency was only going to exacerbate those traits and nurture scandals. The one mildly surprising element of the political conflagration engulfing the White House is how quickly Trump managed to bring it on himself. The president has been a potent accelerant to his own political immolation.

Trump's rash decision to fire FBI Director James Comey last week is proving to be the most politically consequential action of his tenure. After the White House communications office did a miserable job lying about the reasons why Comey was sacked, Trump went on NBC and blurted out the truth: Comey's firing was linked to the FBI's investigation into the Trump campaign's links to Russia. Yesterday, The New York Times broke the news that Trump, while meeting with Comey in February, asked the now-former FBI director to call off the bureau's investigation into Michael Flynn, Trump's former national security adviser.

If this isn't outright obstruction of justice, then it at least shows Trump's willingness to inappropriately use his power and lie egregiously to protect himself and his allies from politically damaging investigations. A president who would so cavalierly abuse his authority and lie about it has forfeited any presumption of good faith and requires a firm check on his behavior from the legislative branch.

Republicans in Congress now face a binary choice: their agenda or the integrity of the political system. Up to this point, the congressional GOP has served mainly to enable Trump's excesses and flagrant misbehaviors because they need him to sign the ObamaCare repeal and regressive tax cuts into law. Every call for meaningful oversight has been brushed aside as Democratic sour grapes, and individual Republicans even took it upon their own initiative to undermine committee investigations into Trump and his associates.

Each time the Republicans defended the White House in the face of scandal or made excuses on Trump's behalf, they sacrificed credibility and made themselves accomplices to the Trump administration's dishonest bungling. But they figured the tradeoff was still worth it if they could just get those bills through.

This time is different. Now they're faced with a credible allegation that the Republican president tried to squash an investigation into one of his political cronies and then fired the guy leading the investigation after he refused to go along. Letting that slide in order to protect tax cuts for the rich would amount to a declaration that a president can get away with pretty much any corrupt act so long as his party controls Congress. Tacitly sanctioning this sort of behavior will just encourage Trump to push the envelope further and hollow out whatever meager public confidence remains in America's governing institutions.

The alternative is for the Republican Congress to actually start reining in Trump's abuses. That means subpoenaing documents, calling in administration officials to testify, pushing committees to investigate alleged abuses, and cracking the whip on a White House that is beyond dysfunctional. A number of congressional Republicans, like Florida Sen. Marco Rubio, won their 2016 races by promising they'd put principle over party and serve as a check on Trump. Those promises have been enthusiastically broken, but Trump has provided the Republicans who made them with ample incentive to rediscover their commitments to non-partisan good government practices.

Going down that road would help restore some measure of faith in Congress as a governing institution, but it would also mean Republicans would have to forsake most of their big-ticket legislative items. There's just no way to muster the political support needed to ram health-care reform and big tax legislation through to passage while Congress is investigating alleged misconduct by the president.

A few Republicans are showing some minimal awareness of the fact that Trump's reckless disregard for governing norms has become a major problem. House Oversight Committee chairman Jason Chaffetz (who is not seeking re-election this term) announced that he will subpoena whatever documents are necessary to figure out what happened between Trump and Comey. His announcement was backed by the House Republican leadership, including Speaker Paul Ryan.

That said, it's still not realistic to expect that the GOP will sacrifice its agenda to flip on Trump. The president remains popular with the party's core voter groups, and Republicans don't want to imperil their congressional majorities by alienating their own base. Right now it still makes more political sense for the GOP to stick with their corrupt, out-of-control chief executive and give him every benefit of the doubt.

The only way their calculation changes is if Trump becomes so politically poisonous that he starts costing Republicans seats, which is precisely why so much attention is focused on the upcoming special elections in Georgia and Montana. And it's well within Trump's capabilities to make himself that toxic. He is, after all, a walking scandal machine, and we still don't know everything Jim Comey knows.