The relationship between President Donald Trump and his allies in Congress is rooted less in a simpatico bond than in a particularly ugly kind of transactional politics.

As is often the case when Trump strikes a deal, his side of it comes first: Republicans tolerate his racism, ignore his corruption, laugh off his erratic behavior, and in exchange he leaves the core of the party’s domestic agenda unmolested. He nominates originalists to the Supreme Court; he breaks all his promises to voters by letting Speaker Paul Ryan set social and economic policy.

Notwithstanding the mythical powers Republicans ascribe to cutting high-income taxes, the terms of the arrangement still leave the country vulnerable to humiliation and grave dangers. Back in November, I argued that this transaction set us in a race against time: Could Republicans squeeze what they wanted out of Trump’s presidency quickly enough to spare the organs of U.S. democracy from fatal damage?

That analysis stands, but may have overestimated Republican competence and underestimated Trump’s toxicity.

Four months later, the devil’s bargain between Trump and the GOP is showing signs of strain. It may come apart before the party has any reward to show for it.