Political parties do not lose their souls or their identities all at once. Usually, it is a gradual process of compromises that make sense in the moment, but which have a cumulative effect — like a frog being gradually boiled.

There are obvious reasons why Republicans have been so unwilling to stand up to President Donald Trump: political tribalism, transactionalism, anti-anti-Trumpism and, yes, timidity. While expressing dismay in private, GOP officials know that the Republican base remains solidly behind Trump. In a hyper-partisan environment, standing on principle can be dangerous for your political health.

But the price of the GOP’s bargain with Trump, however, has continued to rise. Republicans in Congress now not only have to swallow Trump’s erratic narcissism, but also his assaults on the very core principles that supposedly define their politics: fiscal conservatism, free trade, the global world order, our allies, truth and the rule of law.

They know that his crude xenophobia, his exploitation of racial divisions, his chronic dishonesty, sexism and fascination with authoritarian thugs pose a long-term danger to the GOP’s ethical and electoral future. But most remain paralyzed by fear of a presidential tweet. So even when appalled by the casual and calculated cruelty of a Trump policy like separating families at the border, few speak out. And despite expressions of dismay, it seems unlikely that Congress will take any meaningful action to confront Trump’s appeasement of Russia’s Vladimir Putin or to limit this President’s power to launch destructive trade wars. This reticence to challenge Trump is especially striking, given Trump’s propensity for caving on issues like paying for The Wall, when Congress refuses to budge.

Republicans tell themselves they are getting a lot of what they want. (Politics is always transactional, right?) They rationalize their acquiescence to Trumpism by pointing to tax cuts, deregulation and conservative judges. Even if Trump’s conduct becomes indefensible, they can always fall back on attacking Trump’s critics, especially in the media.

Yet what Republicans in Congress have found is that rubber-stampism can be addictive and all-consuming; every time they allow a line to be crossed, it is harder to hold the next one, even if that next one is more fundamental. Republicans have made it clear that they have no intention of providing a meaningful check on Trump, and the next Congress could be even worse: from Georgia to Wisconsin, GOP candidates are vying with one another in their pledges of fealty to Trump rather than to any set of ideas.

As a result, what was once a party of ideas has morphed into a virtual cult of personality. Or perhaps, it was never really a party of ideas at all, but instead merely what Lionel Trilling called a movement of “irritable mental gestures” that was willing to surrender its principles for a slogan on a hat.

The problem for conservatives should be obvious: by failing to stand up for their core values in the face of serial Trumpian outrages, they are effectively letting Trump redefine conservatism. A movement that once insisted that “character matters,” has now internalized Trump’s own moral vacuity, accepting a win-at-all costs ethic, even when the costs are all they said they believed in. Republican elected officials barely raise an eyebrow over evidence that suggests Trump lied about and attempted to cover up hush-money payments to porn stars and Playboy models with whom he had extramarital affairs. The party that once championed free markets now sits by as the President picks winners and losers, proposes massive bailouts and browbeats dissenters in the private sector. Rather than defending constitutional norms, some congressional Republicans have been active participants in the campaign to obstruct and undermine Special Counsel Robert Mueller’s investigation. This week, 11 conservative House members filed articles of impeachment against Deputy Attorney General Rod Rosenstein, who is overseeing the probe.

I suspect that many Republicans imagine that they will be able to reset the party after Trump leaves the political scene. But this seems increasingly naïve; by allowing themselves to become the party of Trump, they make the stain indelible. They are not servants of the public; they are servants to power.

Unfortunately, it’s hard not to see this as a watershed. Republicans have not only ceded ground to the President, they have done so at profound cost to the norms of liberal constitutional democracy. Power ceded is difficult to get back; moral authority squandered is often lost forever. (See: the acceptance of presidential lies, embrace of incivility and indifference to sexual misconduct.)

The problem here is not merely political, but also constitutional. The failure of Republicans to hold Trump accountable underlines what seems to be the growing irrelevance of Congress as a co-equal branch of government. It is unclear whether the courts will fill the void.

No one should celebrate the boiling of the frog. This is not a problem of one political party; the concessions being made by the party in power also makes our politics as a whole dumber, crueler, more isolated from reality and more extreme. In a post-truth, post-ethical world, what do have left to discuss or debate? Democracy requires certain shared understandings of truth and at least a minimal level of respect for moral standards and norms. But we are discovering that none of that can be taken for granted, and at least one political party is no longer interested or capable of defending those values.

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