|The culmination of decades of conservative fear-mongering|
But they did more than that. They built the fact-phobic echo chamber in which conservative voters currently live, that enables them, simply as a force of habit, to shut out any evidence of Trump's abhorrent behavior and inept posturing.
For years, Fox News and the conservative establishment has been pushing the narrative of a biased, liberal media out to persecute conservatives. Facts didn't matter, because they were just smears. Anything, everything, that contradicted what conservatives wanted to hear was a lie; anyone who contradicted the party line was a lying liar telling lies. Anytime conservatives were called on odious behavior, outright lies, or anything else, it was bias, lies, and biased lies.
Which worked really well at insulating the GOP voter base from pesky reality. And, for quite some time, that worked out really well for the GOP establishment, winning them a variety of local, state and national elections.
Only now, the odious behaviors and outright lies from a conservative happen to be coming from one they despise. But they've already constructed such a thorough fact-filtering apparatus that the loyal base is immune. They don't notice, because why would they? Conservatives don't do odious things, and the never lie; it's only biased liars who suggest that they would!
Rightwing media in particular, aided by no small number of conservative politicians, has promoted the idea that conservative feelings about things matter more than actual facts. And now actual facts about Donald Trump are very much at odds with many Republican voters' feelings about Trump. All of a sudden, conservative leadership is worried that their base doesn't care about facts (at least, the targeted subset of facts they want them to focus on), and loves an odious Republican in spite of all his, well, odiousness.
Which would be really, really hilarious if the Cheetos Monster was confined to their section of the lab, instead of threatening to break free and devour everything in his way.
Good job there, guys...