Trump’s big brain. Photo: Chip Somodevilla/Getty Images

In these days of extreme polarization, it’s not unusual to find poll respondents agreeing with outlandish propositions about their partisan heroes and villains. But this one may take the cake:

In response to growing questions about his mental fitness, Trump tweeted a few weeks back that he wasn’t just stable, but in fact a “very stable genius.” Polling since then has asked whether people feel Trump is indeed stable, but the new Washington Post-ABC News poll goes one step further and also asks whether Trump is a genius.

While Americans are about evenly split on his stability, the genius question is decidedly not an even split. Just 21 percent of American adults believe Trump’s intellect rises to the level of a genius, while 73 percent say it does not.

But among that 21 percent is a substantial portion of Republican voters: 50 percent of them, all told. Just 40 percent of Republicans believe Trump is not a genius. So on balance more Republicans buy into Trump’s claim than don’t.

For what it’s worth, only 17 percent of self-identified independents think Trump’s a genius, as opposed to 78 percent who do not. It’s hard to make comparisons to other partisan supporters of other presidents, because no other president has publicly made that claim — not even those who showed signs of deep erudition the cable-news-watcher-who-doesn’t-like-to-read 45th president has never remotely exhibited.

The Post’s Aaron Blake observes that it’s precisely Trump’s self-assertion of his intellectual brilliance that convinces his followers that by God you don’t need no book larnin’ to be a genius:

[T]he Post-ABC poll question invoked Trump in the lead-in: “Trump has described himself as, quote, ‘a very stable genius.’ What’s your own view: Do you think Trump is or is not a genius?” If the question had been simply, “Is Trump a genius?” support would likely have been lower. By invoking Trump, respondents who like Trump get to choose between either agreeing with him or labeling him a liar or exaggerator. The latter choice is not very attractive.

It makes you wonder how Republicans would react if Trump decided to proclaim modesty and self-effacement as among his sterling qualities. Would they agree with that? And if so, what if he fulfilled the paranoid fears of us scribblers and denounced freedom of the press as another “politically correct” habit that needed to be discarded? How many Republicans would say Hell no! to that proposition?

The other side of the polarized coin was exhibited by a couple of different question in the same Post poll: Seventy-five percent of self-identified Democrats do not believe Trump is “mentally stable,”and 57 percent are very concerned (not just somewhat concerned) that POTUS “might launch a nuclear attack without justification.” As a West Coast resident who has had more than one spasm of fear that a weenie-waving contest between Trump and Kim Jong-un might have a terrible effect on my neighborhood, I will not for a moment suggest that “Trump’s unstable” is equivalent to “Trump’s a genius” as a product of pure polarization. But it is another sign that the longing of many well-meaning “centrists” for an outbreak of sweet reasonableness between the parties may be the greatest self-delusion of all.