Witnesses to the rise of Donald Trump have attributed it to the billionaire’s celebrity, the Bush Administration's failures in Iraq, a backlash against left-wing “political correctness,” and the dearth of Republican rivals who combine praise for old-age entitlements with criticism of immigration and free trade. And much has been written about widespread popular disgust with the establishment.

To those factors I would add at least one more.

For years, I’ve argued that talk radio hosts like Rush Limbaugh, Fox News, and websites like Breitbart.com pose a significant threat to movement conservatism. All movements are vulnerable to populist excesses and the self-destructive impulses of their core supporters. Good leaders can help to mitigate those pathologies. Bad leaders magnify them.

Within movement conservatism, hugely popular intellectual leaders abandoned the most basic norms of decency, as when Mark Levin screamed at a caller that her husband should shoot himself; stoked racial tensions, as when Rush Limbaugh avowed that in President Obama’s America folks think white kids deserve to get beat up by black kids on busses; and indulged paranoid conspiracy theories, as when Roger Ailes aired month-after-month of Glenn Beck's chalk-board monologues.

Erick Erickson now complains that many Republicans are supporting “a man of mountainous ego” who “preys on nationalistic, tribal tendencies.” But this is what happens when millions of people spend a decade with Bill O’Reilly in their living rooms each evening and Ann Coulter books on their nightstands for bedtime reading. Let’s not treat it as a mystery that their notion of what’s credible is out of whack.

For years, I’ve complained about egregious displays of misinformation, as when Andrew Breitbart published a video purporting to show a Hispanic Acorn worker willing to engage in human trafficking, but neglected to mention that he only indulged James O’Keefe’s hidden video sting until the amateur filmmaker left, when he called police.

I’ve lamented efforts to portray Democratic leaders as conspirators in a plot to deliberately destroy the country, as when Andrew McCarthy posited that Barack Obama is allied with our Islamist enemy in a “grand jihad” against America. And I warned against the cry-bully ressentiment tapped by Sarah Palin and indulged by her apologists. They accelerated the transformation of the American right away from anything resembling conservatism and toward aggrievement-driven tribalism.

As Andrew Sullivan, David Frum, Rod Dreher, and many other disaffected members of the heterodox right can attest, publishing articles like that attracted nothing but ire from most conservatives, who were loath to acknowledge that the media ecosystem they’d created was every bit as much an absurd echo chamber as the “safe spaces” of Oberlin. Some of them openly resisted the idea that there was any downside to an alliance with intellectually dishonest blowhards. Jonah Goldberg is hardly the worst offender, but his 2009 defense of Glenn Beck is instructive:

Many conservatives believe Beck is undermining conservatism with his often goofy style and his sometimes outlandish and paranoia-tinged diatribes. In an ode to conservatives such as William F. Buckley, my friend Charles Murray writes, “Don't tell me that we have to put up with the Glenn Becks of the world to be successful. Within living memory, the right was successful. The right changed the country for the better—through good arguments made by fine men.” Murray is nostalgic for conservative leaders who were, like Murray himself, soft-spoken intellectuals.

There are problems with such nostalgia. First, there has always been a populist front on the right, even during the "glory days" when Buckley was saying he'd rather be governed by the first 2,000 names in the Boston phonebook than the faculty at Harvard. Moreover, whatever Beck or Limbaugh's faults, they are more cheerful––and more responsible—warriors than the populist right-wingers of yesteryear. The Tea Partiers may be rowdy and ideologically diffuse, but their goals, like Beck's, are indisputably libertarian. And from a conservative perspective, popular libertarian uprisings should be preferable to the sort of statist populism so often celebrated on the left.

Today, the very pathologies that conservatives who should’ve known better indulged as a matter of shortsighted convenience are being exploited by a reality-TV populist whose agenda is far from “libertarian.” His ascension poses an existential threat to movement conservatism. And he cannot be stopped in part because, over many years, conservative media trained its audience to respond to tribal signaling more than rigorous debate; to reflexively dismiss any complaints about speaking disrespectfully about others as bogus “political correctness;” to respond to mainstream-media criticism of public figures by redoubling their trust in them ; to value the schadenfreude of pissing off ideological opponents more than incremental policy gains; and to treat Sarah Palin as a credible candidate for the vice-presidency.

Trump could not succeed but for a large faction that grins at indecency; cheers attacks on Mexicans; sees no need for governing experience; has lost its immunity against populist misinformation and manipulation; believes that establishment officials are trying to destroy the country; elevates cultural cues over substance; and dismisses the possibility of improvement through compromise.

As movement conservatism reaps the pathologies that it sowed (even as its more responsible arms try to kill a monster that they were institutionally complicit in creating), I return once more to the talk radio host who first proved that the base could fall for a polarizing egomaniac with a penchant for crudely insulting women. Rush Limbaugh still purports to be a conservative. Yet he is still engaged in rhetoric so perfectly suited to fueling Trumpism that it is hard to believe he is unaware.

Here is the top of his Web site as I write this article:

The attendant segment was broadcast Tuesday. In it, Limbaugh led his listeners to believe that the Republican and Democratic establishments are conspiring to destroy the last remnants of the America that was born at the Founding—that these elites have nearly completed their plot to have illegal aliens overrun the nation, steal elections for corrupt Democrats, and treat conservatives as state enemies. Lest you think I exaggerate, here’s a condensed version of the monologue in question:

...the objective of the Democrat Party is to take whatever people are in this country illegally and allow them to vote.  That's all this is about.  Everything else is a smoke screen.  It's not about uniting families or keeping them united.  It's not about compassion.  It's not about economics.  It's not about any of it.  It's about expanding the Democrat Party voter rolls…

And now we've closed the circle.  And now we're back at why Donald Trump is in the race and why Donald Trump is running away with it.  You can get as deep or as shallow in the analysis as you want.  But it's about a last chance, a last-gasp effort at preserving the culture that developed after the founding of this country.  It's no more complicated than that, folks.  The country's under siege from all quarters, and recently the Democrat Party has joined those who have put the country under siege.

...people scratch their heads to this day and cannot understand why a single Republican would ever sign on to this… And we're also back reminding everybody that the establishments of both parties continue to be in denial, and maybe they're not.  Maybe they know by now how fully opposed they are and they just got their backs up and they're going, “Well, screw you.  We're still gonna get what we want.  You're the serfs.  We're the elites.  We run the show.  Screw you… If you don't support what they want, you have to be taken care of, you have to be defeated, you have to be rendered irrelevant, you have to be cast aside, whatever.”

...I have a little headline for you here. The New York Post is reporting new legislation is being pushed that would give illegal aliens the right to vote in certain New York City elections… This proposal to grant illegal aliens in New York City the right to vote would result in 1.3 million new voters… In the 2017 elections, they'd be able to vote for mayor, comptroller, public advocate, borough president, and city council.  Just city elections. That's 1.3 million noncitizen residents -- about 500,000 of whom are "undocumented" -- would be able to vote.  That has been proposed in New York City. It's not federal elections, just New York City elections.  But it's already underway, you see, folks.  So discussions of, "Well, if we make the border secure and then..." No, no.  No.  We don't have time for any of that.  We're on the cusp of losing the country.

That's why the anger.

That's why the fear.

It's not just immigration, but it's the biggie.  There's all kinds of other associated, ancillary issues that comprise this.  There's some other things to add to it, just adds a couple exclamation points. Daily Caller: "Almost 60% of Democrats Think Socialism Is Great for America."  It's about preserving the original American culture -- and make no mistake: It's under siege, and has been for a while, and it's losing.  "A clear majority of Democrats believe socialism has a 'positive impact on society,' according to a poll by the American Action Network. The political and economic system that wreaks havoc across the world from Venezuela to North Korea is enjoying widespread support in the modern Democratic Party.

...This whole notion of working together, bringing the country together? We're way past that... We're not gonna unify with the liberal Democrats.  We're not. There's no candidate out there that can forge a kumbaya.

The people on the left, they don't want to reach common ground with us.  We are gnats to them, or worse.  We are the Gestapo to them.  We're Nazis to them.  We are standing in the way of whatever they want.  

These people have to be defeated.  They have to be overwhelmed.  And then after they're defeated they cannot be allowed to bully whoever wins into cowardice and caving in… if you believe in a certain cultural America, it's under siege.  There's nothing to join with on the other side in preserving it.  They want to tear it down, transform it, and rebuild it.  They have to be defeated.  This is why the Republican Party's worthless.  They don't even think this way. The Republican Party's thinking about showing they can work together, they can cooperate, make Washington work...  

...we've got people coming at us that are gonna try to wipe us out and eliminate everything and pretend it didn't happen, corrupt, sabotage, undermine. Whoever the next president is, and whoever's running the next Congress, and whoever nominates the Supreme Court justice, if it's a conservative, you have no idea what's gonna be brought to bear! We're gonna need people with such backbone and guts and steel and iron to hold up and to withstand what's gonna come at 'em, you can't even imagine it.  

That is the message of the most popular entertainer in the conservative movement, a man hosted by Republican presidents at the White House, honored by the Heritage Foundation and the Claremont Institute, and lauded at one time or another in most every movement publication. In his funhouse-mirror telling, today’s obstructionist Republicans are all about cooperating in Washington. The illegals are coming to steal American elections, they’re shock troops for an all-powerful left that will snuff out the last remnants of the Founding, and folks with heartland values will be squashed unless a strongman with unprecedented backbone stands up to Democrats and illegals and socialists who’ll otherwise treat conservatives like Nazis.

If you believed all that was true––if you took it not as hyperbolic entertainment, but an earnest assessment of the state of the union from the stalwart who gives it to conservatives straight––perhaps you’d seriously consider voting Donald Trump, too.