The Republican establishment, which has always distrusted and discounted Donald Trump, is getting increasingly nervous.

So nervous, in fact, that some of its media voices are starting to denounce their party’s front-runner in the strongest possible terms.

As in, refusing to vote for the man if he’s the nominee. As in, loudly proclaiming that he will destroy the GOP.

Viewed from one perspective, this has the smell of panic. Viewed from another, it’s a case of party stalwarts speaking out based on principle.

For decades now, there has been primary-season sniping between the establishment wing and the insurgent/hard-line/Tea Party wing. Commentators rough up their least favorite candidate, even declare them unqualified for the White House.

But if that person prevails—think Mitt Romney in 2012—the sharpest Republican critics find a way to walk it back. Well, he wasn’t my first choice, but he would be better than Barack Obama. He’s evolved on immigration/tax cuts/ObamaCare. He would pull this country out of its left-wing tailspin.

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These days, the rhetoric is getting so hot that there will be no scrambling back on board. Bill Kristol has been openly musing about a third party if Trump wins the nomination.

Does the conservative media elite hope to throw some tacks under the Trump steamroller with such sharp rhetoric? Or are its members just speaking out to clear their consciences?

If it’s the former, I think it might actually help Trump to have the Beltway types arrayed against him. These are the folks he is running against, and he’s never positioned himself as a doctrinaire conservative.

Michael Gerson, a Bush White House official who writes for the Washington Post, uses sweeping language:

“Trump’s nomination would not be the temporary victory of one of the GOP’s ideological factions. It would involve the replacement of the humane ideal at the center of the party and its history. If Trump were the nominee, the GOP would cease to be.”

Cease to be. That’s pretty historic stuff.

Gerson calls Trump a “demagogue” who “has followed some of America’s worst instincts wherever they have led, and fed ethnic and religious prejudice in the process. All presidential nominees, to some extent, shape their parties into their own image. Trump would deface the GOP beyond recognition.”

In case you missed the point, Gerson says: “Trump is disqualified for the presidency by his erratic temperament, his ignorance about public affairs and his scary sympathy for authoritarianism. But for me, and I suspect for many, the largest problem is that Trump would make the GOP the party of racial and religious exclusion.”

Doug Heye has been communications chief of the RNC, a top deputy to Eric Cantor and a Bush administration official. He makes a personal declaration in the Independent Journal:

“Because of Trump’s perversion of conservatism, along with the devastating impact he would have if nominated, I cannot support Donald Trump were he to win the Republican nomination.”

Heye says Trump would be “dangerous to the United States and the world at a time when the world is at risk.” His nomination, says Heye, “would be catastrophic for Republican hopes to win the White House and maintain control of the Senate and would damage the party and the conservative cause for years to come. His having the legitimacy that comes with the nomination of a major political party would cause greater instability throughout the world at a time when the world looks to America for leadership that is serious and sober.”

This is the New York Times’ latest version of the same story, calling it a “people’s coup”:

At family dinners and New Year’s parties, in conference calls and at private lunches, longtime Republicans are expressing a growing fear that the coming election could be shattering for the party, or reshape it in ways that leave it unrecognizable.

But a very different tack from Peggy Noonan, who worked for Ronald Reagan and George H.W. Bush, who turns the question back on the establishment:

“I do not understand the inability or refusal of Republican leaders to take Mr. Trump seriously. They take his numbers seriously—they can read a poll—but they think, as Mr. Bush said, that his support is all about anger, angst and theatrics. That’s part of the story, but the other, more consequential part has to do with real policy issues. The establishment refuses to see that, because to admit it is to implicate themselves and their leadership. Political consultants can’t see it because they don’t think issues matter—not to them and certainly not to the dumb voters.

“But issues do matter, and Mr. Trump has functioned this year not as a great communicator or great compromiser but as the great disruptor. He brags that he has brought up great questions and forced other candidates to face them and sometimes change their stands—and he has.”

There really isn’t much of an establishment left. It consists of some megabuck donors, elected officials, seasoned operatives and media pundits. They don’t have the power to stop Trump, and they know it.

The best they can hope for is to influence the debate. Their problem is that most of them don’t like Ted Cruz, either.

Howard Kurtz is a Fox News analyst and the host of "MediaBuzz" (Sundays 11 a.m. and 5 p.m. ET). He is the author of five books and is based in Washington. Follow him at @HowardKurtz. Click here for more information on Howard Kurtz.