The Republican Party nominated Donald Trump as its candidate for president of the United States – and I responded ending my 44-year GOP membership.

Here's why I bailed, quit, and jumped ship:

First, Trump's boorish, selfish, puerile, and repulsive character, combined with his prideful ignorance, his off-the-cuff policy making, and his neo-fascistic tendencies make him the most divisive and scary of any serious presidential candidate in American history. He is precisely "the man the founders feared" in Peter Wehner's memorable phrase. I want to be no part of this.

What a real conservative looks like: Margaret Thatcher with the author, 1996.

Second, his flip-flopping on the issues ("everything is negotiable") means that, as president, he has the mandate to do any damn thing he wants. This unprecedented and terrifying prospect could mean suing unfriendly reporters or bulldozing a recalcitrant Congress. It could also mean martial law. Count me out.

Third, with honorable exceptions, I wish to distance myself from a Republican Party establishment that made its peace with Trump to the point that it unfairly repressed elements at the national convention in Cleveland that still tried to resist his nomination. Yes, politicians and donors must focus on immediately issues (Supreme Court justice appointments) but party leaders like GOP committee chairman Reince Priebus, House Speaker Paul Ryan, and Senate Majority Leader Mitch McConnell wrongly acquiesced to Trump. As columnist Michael Gerson wryly notes, Trump "attacked the Republican establishment as low-energy, cowering weaklings. Now Republican leaders are lining up to surrender to him – like low-energy, cowering weaklings."

Fourth, the conservative movement, to which I belong, has developed since the 1950s into a major intellectual force. It did so by building on several key ideas (limited government, a moral order, and a foreign policy reflecting American interests and values). But the cultural abyss and constitutional nightmare of a Trump presidency will likely destroy this delicate creation. Ironically, although a Hillary Clinton presidency threatens bad Supreme Court justices, it leaves the conservative movement intact.

Finally, Trump is "an ignorant, amoral, dishonest and manipulative, misogynistic, philandering, hyper-litigious, isolationist, protectionist blowhard" in the words of Republican donor Michael K. Vlock. That charming list of qualities means supporting Trump translates into never again being able to criticize a Democrat on the basis of character. Or, in personal terms: how can one look at oneself in the mirror?

And so, with Trump's formal nomination, I bailed.

For the Republican Party to recover its soul, Trump needs to be thumped in November. Purged of his influence, the party of Lincoln and Reagan can rebuild.

In the meantime, I shall support other Republican candidates, notably Pennsylvania's excellent Senator Pat Toomey. As for president? Either the libertarian Gary Johnson, a write-in candidate, or no one at all.

Mr. Pipes (DanielPipes.org, @DanielPipes), has served in five presidential administrations. © 2016 by Daniel Pipes. All rights reserved.

July 21, 2016 addenda: (1) I address criticisms of this article at "Blowback from Criticizing Trump."

(2) I document who else has taken this step at "Who Publicly Quit the Republican Party Because of Trump."

May 30, 2017 update: I worried about Republicans losing their way in terms of ideas; it did not occur to me that they would adopt a host of Trump's foul behaviors. But such is the case, Max Boot documents today at "From the Party of Lincoln to the Party of the Body Slam." This confirms my decision not to be a Republican.

July 27, 2020 update: Bret Stephens notes, almost exactly four years after the above article was published, that "it will probably take more than one electoral shellacking for conservative-leaning voters to appreciate the scale of disaster that Trump's presidency inflicted on the party and the country."