This is the GOP’s future if Donald Trump wins.

In Republican primaries, opportunists will try to mimic Trump’s ugly brand of identity politics and actual white nationalists will be emboldened to vie for power in the GOP. They will win in some regions and transform the tenor of local politics in many more, alienating a broad swath of Americans on the right and the left. If you don’t believe me look at how people already behave at Donald Trump rallies.

That faction may become the bane of all other Republicans.

The trajectory would do great harm to the conservative movement and the progressive left, so much so that it’s in their mutual interest to cooperate to stop it. If Trump fails––especially if he loses in a humiliating landslide––the defeat will go a long way toward discrediting that same brand of right-wing identity politics, putting the GOP on a trajectory that would benefit conservatives and progressives alike.

It would, however, benefit them in different ways.

Why Conservatives Should Fear White Identity Politics

The self-interested reason for conservatives to fear white identity politics is demographic: there’s an expiration date on any coalition that wins white men without college degrees but alienates a “Rainbow coalition” that includes college-educated whites. That date may have already passed. Imagine choosing now, of all moments, to run a campaign that actively antagonizes Hispanics who were born in the United States.

Regardless, it dooms movement conservatism in the long term.

And even if Trump wins this year, there is reason for conservatives to fear the identity politics he embodies and inspires even in the short term. That is partly because he will embrace redistributionist big government, albeit an iteration that directs its spoils to different constituencies. His efforts will displace much of what existing factions in the GOP hold dear: Neither social conservatives nor libertarian-leaning Republicans nor neoconservatives will gain standing. All may lose it.

The cultural debate about political correctness will be transformed as the face of what’s “politically incorrect” changes from, say, a college professor embroiled in a Kafkaesque “bias investigation” for failing to issue a “trigger warning,” to a xenophobic demagogue insulting the parents of a fallen Muslim American soldier.

And as Republican governors in blue states and representatives in purple districts find themselves having to distance themselves from Trump’s agenda to retain their seats, the president himself will have a greater incentive to pander to his base—that is, the part of the GOP coalition that is least motivated by principled conservatism and most motivated by racism, xenophobia, and economic protectionism.

Why ‘Bernie-or-Busters’ Should Go All In Against Donald Trump

If a Donald Trump victory would do so much harm the to conservative movement, why would it be in the interest of progressives—especially progressives with an intense dislike of Hillary Clinton—to work to oppose that outcome?