The recognition—dawning rapidly on a gainsaying political establishment—that Donald Trump is poised not just to win more delegates on Super Tuesday than other GOP candidates, but to completely dominate this week’s 13 nominating contests, has confronted movement conservatives and loyal Republicans with a time for choosing.

The forces propelling Trump toward victory are driving party actors toward one of two determinations: Either Trump is the future of a Republican Party that current Republicans can live with, or the Republican Party is unsupportable with Trump atop its ticket. The latter would invite the kind of massive political realignment that only occurs in this country once or twice a century.

On Friday, former presidential candidate Chris Christie—the governor of New Jersey, and recently the chairman of the Republican Governors Association—made his choice clear by endorsing Trump. Moments later, Maine Governor Paul LePage followed suit. On Saturday, former Arizona governor Jan Brewer joined those two, and on Sunday, Senator Jeff Sessions of Alabama made it a foursome

The counterweight to these conformists is embodied by #NeverTrump—a trending social media topic popularized by conservative activist Erick Erickson, and adopted most notably by Marco Rubio—which serves as a calling card for conservatives who are refusing to support Trump in a general election. The implication (which Rubio has refused to spell out directly) is that he will refuse to endorse Trump should he win the GOP nomination. 

If this represents an enduring schism—if the ranks of resolute anti-Trump conservatives grows to include influential Republicans who had previously pledged to support the winner of the primary unconditionally—the significance will be hard to overstate. By closing in on the nomination, Trump is pitting conservatives’ commitments to party and movement against one another. If most Republicans were to fall into line behind Trump, the Republican Party apparatus would reorient dramatically, but it would survive. If instead the party’s leaders abandon Trump after promising otherwise, they would turn millions of people against the GOP enduringly. The damage to the Republican Party as an institution would be profound, perhaps fatal.

Trump’s nomination by itself would deal a huge blow to conservative movement infrastructure. The movement has thrived on the impression that it is the institutional and well-heeled face of a vast grassroots composed of committed, principled, ideological voters–a potent combination that allowed it to take over the party. Trump’s nomination would demonstrate that the movement was founded upon illusions—that it’s unable to shape campaigns, and that it represents an electorate that is actually more demagogic than philosophical. 

If Rubio and other key GOP figures abandon Trump, they will be in effect committing to rebuild a similar ideological movement—with the critical difference being that the new one will be shorn of the power to wield resentment and racial grievance to advance its ends. That poses a huge challenge to the imagination. The existing conservative party has become practically coextensive with the politics of resentment and grievance. It’s almost impossible to think up a version of the GOP that has cashed them out to a breakaway Trump faction. 

To understand why, look no further than this very election, which has been defined, with few exceptions, by Republican hopefuls following Trump’s lead and appealing to his supporters. At the same time, Trump has co-opted and amplified articles of conservative faith (that President Obama is a disaster, that America is weak) in ways that will make it extremely difficult for Republican leaders to disavow Trump without also disavowing the grievance and resentment, too. 

For instance, consider how feckless the Republican establishment’s attacks on Trump have been thus far, and how unpersuasive a standard-issue Republican candidate would be in a general election campaign against him.

It is untenable to attack Trump for advancing a ludicrously skeletal alternative to the Affordable Care Act, when the Republican Party has no alternative of its own, and Trump’s competitors offer little more clarity.

It is untenable to attack Trump for fiscal profligacy when nearly all conservative elites are aligned in consensus that the country urgently needs huge, regressive tax cuts, much more defense spending, and absolutely no immediate cuts to Social Security and Medicare.

It is untenable to attack Trump for refusing to say how he will provide health coverage to everyone—a pledge he’s repeatedly made—when Republican leaders suggest their Obamacare alternatives, which will strip coverage from millions of Americans, won’t disadvantage anyone.

It is untenable to attack Trump for promising to deport 11 million immigrants if you’ve built party politics on the impression that the country is being inundated by immigrants, invaders, ISIS infiltrators, and disease carriers. 

It is untenable to pretend that Trump’s promise to finance a wall on another country’s budget is somehow less fantastical than promising to sow enough chaos in immigrant communities that they’ll leave the United States on their own.

It is untenable to attack Trump for saying the IRS might be auditing him because he’s such a “strong Christian” when you’ve convinced nearly half the country that the IRS needs to be reined in or abolished because it has been illegally targeting Christians and conservatives in a campaign of political retribution.

It is untenable to attack Trump for being unelectable when you’ve convinced nearly half the country that the other party’s frontrunner is going to be indicted by the Justice Department for endangering national security.

It is untenable to attack Trump for refusing to disavow David Duke when a a guy who once described himself as “David Duke without the baggage” is now the third most powerful Republican in the House of Representatives.

Remove this immense capacity for bullshit and self-deception from the party’s political arsenal—or at least render it ineffective—and it’s hard to envision what mobilization tools (and thus what policies) would replace it. There is an optimistic scenario in which a reconstituted conservative movement organizes around a more productive, less uncompromising politics. 

A new Republican Party (formed to confront Trump in the election, or in the aftermath of his defeat) would perhaps be more consistently attuned to the social concerns of religious voters—pairing existing religious-right commitments like opposition to abortion and same-sex marriage with a more progressive distributive agenda aimed at reducing poverty and encouraging family growth. A party like that would be able to vie for Trump’s supporters by promising to lift them up, rather than by stooping to their level, and would insure their losses among secular whites by appealing to devout but ideologically non-doctrinaire churchgoers. 

This might not describe the pluralistic, tolerant Republican Party of liberal dreams, but it beats most of the easily imagined alternatives. If Republicans rally to Trump and he loses, it will embolden the purist, maximalist faction of the party led by Ted Cruz all over again. This faction will plausibly claim that, but for Trump, an orthodox conservative would have won the nomination and the presidency. Republicans will deploy the tactics they used against President Barack Obama against President Hillary Clinton, but with much more uniformity and zeal. On the other hand, if Republicans rally to Trump and he wins—well, then liberals will face more pressing concerns than gaming out the GOP’s uncertain future, or wondering what will become of the conservative movement as we know it.