How did Fox News star Sean Hannity mutate into such an intractable foe of the Republican Party establishment?

Of all the evidence that Donald Trump has been turning the body politic into twitching mass of crazy—while demolishing quaint traditions of fact-based argument and coherent speech, upending time-honored conventions of acceptable discourse, and, by most accounts, taking a wrecking ball to a 162-year-old American institution—Hannity is perhaps the most poignant example.

Somehow, a potty-mouthed reality-show billionaire—a tabloid-ready libertine who until very recently was a proud pro-choice Democrat, a fan of government entitlements, and a friend and admirer of Bill and Hillary Clinton—has managed to mesmerize the mainstream media and a significant swath of the electorate as well as Hannity’s afternoon drive-time radio audience of more than 13 million listeners, plus nearly two million Fox News viewers.

So Hannity—out of ideological conviction or, more likely, his acute market sense and show-business savvy (and perhaps an unattractive lickspittle ambition to be a well-positioned courtier)—has gone full-Trump, and did it many months before his formal endorsement of the Celebrity Apprentice candidate in June.

The 54-year-old cable television and talk radio personality, once a reliable interpreter of Republican National Committee talking points into the everyman argot of his white working-class Long Island roots, is trashing treasured icons and bedrock principles he apparently used to revere.

Free trade? Scratch that. Balanced federal budgets? Forget it. Entitlement reform? No longer important. And what about America’s commitment to NATO and opposition to Vladimir Putin’s expansionism? Apparently that’s not a vital concern either.

Sadly, my requests to GOP officials, conservatives and others to offer perspective on Hannity’s jihad against his fellow Republicans went unanswered.

This week he has been escalating his attacks on the Senate Republican Majority Leader Mitch McConnell; the Speaker of the House Paul Ryan; the former Republican presidential nominee, Arizona Sen. John McCain; and even New Hampshire Sen. Kelly Ayotte (the latter two engaged in tough reelection battles, made much tougher by Trump, who figures to lose both their states to Clinton).

Their inexcusable sin was to quibble with some of Trump’s more outrageous blurtings (banning Muslims, slagging off “Mexican” judges and the like), while loyally if painfully maintaining their support for the GOP standard-bearer.

These are all politicians, by the way, that Hannity cozied up to in the past, drawing them out in softball interviews that are more recognizable as infomercials than actual conversations.

He also has been rubbishing former 2016 candidates Jeb Bush, John Kasich, Lindsey Graham, and Ted Cruz—longtime champions of the Republican cause who, in Hannity’s defense, have indeed withheld their endorsements from his fair-haired, combed-over hero.

Perhaps not as surprising but equally entertaining: Hannity’s Twitter slap-fest in recent days with #NeverTrump pundit Bret Stephens, deputy editorial page editor of The Wall Street Journal and, as such, a card-carrying member of the media-political elite that college-dropout Hannity probably genuinely resents.

“Fox News’ dumbest anchor,” the Pulitzer Prize-winning, hyper-educated Stephens (University of Chicago, London School of Economics) tweeted Thursday night in response to Hannity’s latest tirades against the Republican Party leadership.

This prompted a near-midnight primal scream Thursday from the multimedia motor-mouth, who unleashed an occasionally R-rated retaliatory strike.

“If Hillary wins I will hold assholes like you accountable,” Hannity tweeted at Stephens. “You will be responsible for her Supreme ct selections.”

During his radio show Thursday and Friday, a clearly stung Hannity continued his attacks on Stephens—who, having been raised in Mexico City, the son of a chemical company executive, might have been among Trump’s alleged “rapists” and “drug dealers” denied entry into the United States three decades ago if Trump’s “beautiful wall” had been built back then.

“This is an elitist that with all his purity towards the Republican Party—you know, I’m the dumb one,” Hannity ranted on his radio show. “Well, he’s a dumbass with his head up his ass because this is why this country is in decline.”

On Twitter, Hannity took on the threatening bully-boy persona familiar to the followers of @realDonaldTrump: “I love kicking your ass,” he informed Stephens, “and showing Twitter what an arrogant, out of touch elitist you are. #fun.”

Hannity opened Friday’s radio show by heaping additional insults on Stephens—“the idiot from the Wall Street Journal.”

Clearly enjoying his time in the sun, Stephens tweeted back: “Fox News’s Dumbest Anchor is also its most thin-skinned.”

In a second tweet, Stephens asked: “Why does @seanhannity remind me of Otto from ‘A Fish Called Wanda’?”—and then linked to a clip from the 1988 movie comedy in which Jamie Lee Curtis’s character dresses down the Otto character played by Kevin Kline: “To call you stupid would be an insult to stupid people! I’ve known sheep that could outwit you! I’ve worn dresses with higher IQs! But you think you’re an intellectual—don’t you, ape?”

Stephens messaged The Daily Beast: “I’ll let Jamie Lee have the last word for me.”

Meanwhile, on Thursday, Hannity warned the leaders of his troubled political party: “If in 96 days Trump loses this election, I am pointing the finger directly at people like Paul Ryan and Mitch McConnell and Lindsey Graham and John McCain. I have watched these Republicans be more harsh toward Donald Trump than they’ve ever been in standing up to Barack Obama and his radical agenda.

“They did nothing, nothing—all these phony votes to repeal and replace Obamacare, show votes so they can go back and keep their power and get reelected. Sorry, you created Donald Trump, all of you. Because of your ineffectiveness, because of your weakness, your spinelessness, your lack of vision, your inability to fight Obama.”

Hannity was even unpersuaded by aspiring peacemaker and former House speaker Newt Gingrich, his “very dear friend” and mentor from his days a quarter century ago doing rightwing radio in Atlanta.

Gingrich was also the beneficiary of Hannity’s private jet largesse when he was one of Trump’s vice presidential possibilities last month and needed a ride to Indiana to meet with the nominee.

Yes, Hannity, the working man’s populist, whose radio contract alone is said to be worth $20 million annually, only flies private and has done so for many years.

Still, “Hannity’s not that far-out removed from the days of washing dishes and cooking and bus-boying and waitering and bartending,” he claimed on Friday’s radio show, name-checking himself in the third person with Uriah Heep-ish humility. “I’m not that far removed from painting houses and hanging wall paper and laying tile and framing and roofing and falling three stories off a roof and busting up my arm and my face and my teeth. I’m not that far removed from living paycheck to paycheck and having no money in the bank to pay for anything. And I see these other Americans that are following me—they don’t have the ladder that I had.”

Presumably, he was referring to a metaphorical ladder—not one needed for climbing on a roof.

Gingrich had called in to offer a tepid defense of Paul Ryan and John McCain and their rock-and-hard-place dilemma of trying to keep their seats, and Republican control of Congress, in the event of a Clinton landslide in November.

“I’ll be honest. I’m very disappointed in John McCain,” Hannity complained to Gingrich. “I’m very disappointed in all these other people. I just am. I feel like they’re openly sabotaging” Trump.

Hannity took the night off his Fox News show Friday, so he didn’t have an opportunity to explain or otherwise apologize for his champion’s dutiful, hostage-video endorsements of Ryan, McCain and Ayotte—the very same miscreants that Hannity had been railing against.

But if past is prologue, now that the king has called the new tune, Hannity will soon be dancing the necessary steps.