That is the "existential" choice facing Republican leaders, explains Brian Beutler at New Republic.
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.
The we can live with Trump alternative
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 Never Trump alternative
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.
What the split might do
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.
And, as Trump has implied, if the Republicans do not "play fair" he will hurt them more than they hurt him. I guess that might mean a 3rd party run.
So, the Republican elite is in a real jam. Moreover, to turn on Trump would be to undermine the whole set of core beliefs that they have foisted upon their base.
... 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.
Here are just a few instances.
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 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.
And so on - read Beutler's article for more.
My guess? The split will be resolved in favor of Trump's nomination. My confidence? A wee bit over 50/50.