It’s Donald Trump’s party now.

The party of Lincoln, Roosevelt and Reagan, weakened by corruption and compromise, has been conquered. A virulent new strain of nativism has prevailed.

Congratulations, however bitter, are in order to Trump and his followers. You have pulled off an extraordinary feat. You have made history. That has to be acknowledged.

But like many other Republicans, I won’t be joining you. I can’t. My innards won’t let me. I don’t say that out of resentment or poor sportsmanship. I’ve always pushed those instincts aside after primaries and rallied to the nominee. But I cannot this time. I would sooner turn my brothers in to the Stasi or leave my children with a stranger.

To me, backing Trump would mean disloyalty to my country. And I won’t do it.

I realize a plurality of Republicans feel the opposite way. I know you see Trump as America’s savior. Some of you are friends.

But to us — to me — Trump is an irresponsible choice, a reckless choice. Eccentric mayor of Palm Beach? Sure. President of the United States? Never. It would be rolling the dice with everything on the line.

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Why would you do that?

Any one of a dozen Trump statements should be a disqualifier for the Oval Office. Purposely murdering the families of our enemies is a war crime. So is torture. Both would surrender U.S. moral authority in the world, not to mention putting Americans at greater risk of violence. Creating a database of American Muslims is the stuff of the Gestapo. Encouraging nuclear proliferation in the Pacific Rim is incomprehensibly dumb.

The true collapse of the Republican Party won’t come from Trump, though. It will come as Republican leaders succumb to him and his angry populist wave. They think they can harness it. They think they can feed the crocodile. But it will strip them of their dignity, then devour them whole. Crocodiles can’t be tamed.

America’s political revolt is occurring because of corruption in both parties. Not cash-under-the-table corruption, although that happens, too. I mean institutional corruption. Government has become so big, so powerful and so interwoven with financial interests that it now exists chiefly for its own benefit. Ask anyone in Congress a simple question. Chances are you’ll hear back, “Well, it’s complicated.”

Where did clear thinking unadulterated by electoral considerations go? What happened to the party that risked everything to end slavery? In its place we have “complicated.”

I awoke Wednesday morning realizing that I no longer fit comfortably in any national party. It makes me think a new one is coming. There are too many of me out there. In the meantime, I have switched my registration to the New York State Conservative Party, with which I agree on most issues, especially on the need to restrain government.

Another disturbing thing struck me, although it’s been hard to escape notice for awhile. Americans are becoming meaner. I went through my overnight Twitter feed and the most-retweeted item, from both the right and the left, was a slow-motion video of Texas Sen. Ted Cruz inadvertently elbowing his wife in the face at his concession speech.

From what underbelly of rage and moral decrepitude does meanness like that spring?

I fear it’s from the underbelly that just digested my party.

William F. B. O’Reilly is a consultant for Republicans.