It’s usually easier in hindsight to see the seeds of war as they were sown, or to spot small rifts before they became empire-destroying fissures. The breakup of the Republican Party is recognizable in real time.

Tuesday provided the latest milestone on the road to GOPerdition. All three remaining candidates in the race disavowed their previous pledges to support the eventual Republican nominee. A former candidate, Marco Rubio, is taking the drastic, and reportedly unprecedented, step of trying to maintain control over the 170-plus delegates he won before dropping out of the primary.

What do you call a political party whose also-rans won’t rally ’round the winner? I don’t know, but it’s not a political party anymore.

Of course, the latest maneuvering and pledge-breaking revolves around one man. Donald Trump is the reason party officials instituted the pledge in the first place, as they feared he would bolt for an independent run. Now that looks like a best-case scenario, in which Trump would leave the GOP to rebuild itself absent the hateful, fact-challenged and increasingly violent rump of his support he not only attracts but encourages.

That Trump would blame his (latest) infidelity on a belief he has been "treated very unfairly" is just one more absurdity to come out of his mouth. In fact, the party has been far too fair to Trump — suicidally so, it appears.

Had any other candidate mocked a previous nominee for being captured in Vietnam, referred to one female journalist’s menstrual cycle, and made excuses when his campaign manager was charged with simple battery of another female reporter, among other outrages, the Republican Party would have banished him. Trump has been allowed to remain, out of concern his dismissal would tear the party apart.

Instead, it’s his presence that’s doing the job.

So much for the “establishment” against which Trump, like his nearest rival, Ted Cruz, rails. If there were such a powerful cabal of party leaders, they long ago would have cut Trump down. His very success shows he’s been attacking a straw man.

But if his success has shown just how vacuous the notion of a GOP “establishment” is, it has also revealed the emptiness of the “Republican” label itself.

Is a Republican for trade deals, or against them? For peace through strength and alliances, or for ditching NATO? For equality of opportunity (not outcome) for all, or only for some? For modesty about what the federal government can and should do, or for a Constitution-ignoring strongman as long as he’s our Constitution-ignoring strongman?

So far, GOP primary voters have signaled through their ballots that they’re for all these things, which really means they’re for none of them. For all the left’s portrayals of Republicans over the years as rigid ideologues, the irony is the Republican Party is falling apart because it no longer actually stands for anything.

Trump didn’t so much create this incoherence as exploit it. His mistake, and that of his supporters, is pretending his own incoherence represents a viable alternative.

Nope. When anyone believing just about anything can call himself a Republican, everyone’s a Republican In Name Only. And when that’s true, the name is no longer even worth anything. All that’s left now is to figure out what replaces it.