It's becoming a pattern. Jeff Flake, Arizona's junior Republican senator and occasional Trump critic, announced last week that he's giving up his seat, and in the process unleashed tirades against President Trump, basking in media plaudits afterward. This is exactly what happened with Tennessee Sen. Bob Corker earlier this month. John McCain and George W. Bush have also stood on soapboxes to not-so-subtly subtweet America's 45th president.

We seem to be approaching a critical mass not just of establishment GOP dissatisfaction with the president, but the loud public voicing of this dissatisfaction. I feel all but certain that we're seeing the early signs of this eventuality: There will be a Republican establishment primary challenge against President Trump in 2020.

I don't believe there's a conscious or coordinated effort to oust Trump (though there might be). But there doesn't have to be. There is too much GOP money that wants Trump gone, too many GOP establishmentarians who would love to see Trump fall. The invisible primary is beginning.

And it's going to be a disaster.

The GOP establishment is intellectually bankrupt, endlessly reciting the same one-line promises from the 1980s and thinking it passes for an agenda. The GOP establishment is also morally bankrupt, bearing responsibility for (among other things) the Iraq War and years of terrible economic mismanagement. Even worse, the GOP establishment seems blissfully unaware that it, and not everybody else, is the one with the problem.

President Trump enjoys an 80 percent approval rating among Republicans, according to Gallup. The implicit anti-Trump Republican narrative seems to be something like: Trump keeps stumbling and screwing up, so at some point his flaws will become apparent to Republican voters, and they'll wake up and come back to the establishment.

This is delusional.

Most Republican voters are fully aware of Trump's various flaws. But they think the alternatives on offer by the GOP establishment are worse.

A New Yorker cartoon went viral awhile back because it summarized the elite feeling about Trump's populist appeal. It shows the inside of an airplane cabin; one passenger stands up and proclaims: "These smug pilots have lost touch with regular passengers like us. Who thinks I should fly the plane?" as the other passengers enthusiastically raise their hands. Zing! But, as a friend muttered upon seeing the cartoon, if the pilots are flying the plane into a cliff, this is actually the most rational course of action.

Put aside whether this framing reflects reality accurately; it accurately reflects primary voters' perception of reality. They think the establishment is flying the plane into a cliff. They'd rather a neophyte like Trump fly the plane.

Trump is teflon-coated. It doesn't matter if the establishment points out that he makes military widows cry. First off, many Republican voters have been brainwashed by Fox News into believing such allegations are #fakenews. But more importantly, when they hear it from an establishment GOP politician, they think something like, "Yeah, he made one widow cry, and you turned thousands of military wives into widows by lying about Iraq."

2020 will not be a repeat of 2016, when Trump only ever got a plurality of the vote until he was the last man standing. He will be the president of the United States and the Republican Party's incumbent and presumptive nominee. He will combine the advantages of a populist candidate — rhetorical excess, a passionate core of supporters — and all the advantages of institutional support, however reluctant, that come with incumbency.

He will destroy his establishmentarian challenger. What's more, the challenge will help him in the general, because it will distance him from everything that swing voters hate about the GOP — congressional dysfunction, slavish devotion to big business, and smarmy self-righteousness.

The GOP may want to take down Trump. But it's too late. If they rise up against him, he will crush them.