Ohio Gov. John Kasich greets supporters after a town hall meeting Tuesday in Annapolis. (Chip Somodevilla/Getty Images)

Of all the mysteries of this very mystifying political season, none is more baffling than the Republican Party’s determined refusal to nominate Ohio Gov. John Kasich for president.

On paper, he makes sense. He’s a tax-cutting, budget-balancing conservative with 18 years in Congress under his belt, plus a term-and-a-half leading the nation’s seventh-largest state. Kasich’s state has 18 electoral votes, which Republicans need in November; he is popular there, with a 62 percent approval rating.

What’s more, in 15 head-to-head polls during 2016, he beat Hillary Clinton every time, by the margin of error or greater, according to RealClearPolitics. Both Donald Trump and Sen. Ted Cruz (R-Tex.) consistently trail the Democrat.

Familiar, conservative, electable: What’s not to like? Yes, yes — he’s a rambling orator, at best, and notoriously peevish. But having met Kasich and listened to him talk about the issues with The Post’s editorial board for more than an hour Wednesday, I’ve got a hypothesis about why he’s failed — and it has nothing to do with his quirks, which were mostly under control during our session.

Kasich’s problem is that he’s not apocalyptic.

Republican presidential candidate John Kasich talks to The Washington Post about the race to win delegates, Donald Trump and race relations in the U.S. (The Washington Post)

U.S. unemployment and economic growth are better than in most industrial countries; international security is dicey but contained. For GOP primary voters, though, it’s axiomatic that President Obama’s America is going to hell in a handcart. More than 80 percent of them told a Rand Corp. survey in December that the country is “off on the wrong track.”

That number barely scratches the surface of GOP discontent. In March, the Pew Research Center found that 66 percent of the party rank-and-file believe life is “worse” for people like them than it was a half-century ago. Some 64 percent feel it will be even worse for the next generation. In both respects, GOP negativity was greater by double-digit margins than that of the general public.

To this epic angst, Kasich responds with a message that’s not so much sunny as it is conventional: “I get that. But my idea is we can fix it — these things can be fixed. And I think we’ve overdramatized our situation. I’m not being coldhearted here, but we’ve had worse times in this country — far worse times in this country. We’ll be fine.”

He touted his record in Ohio, his policy proposals, the “spirit” of ordinary folks. He forgot to hate the mainstream media, praising the “responsible” role of The Post and other major dailies — even lauding the New Yorker, whose subscriber list is not in high demand with GOP fundraisers.

These are the sorts of things you say when you think it’s still important to curry favor with editorial boards, and that voting is still an instrumental exercise — a choice about the best person to entrust with the Oval Office for four years.

Alas for Kasich, Republicans this year seem to be voting as a form of expressive conduct — a statement about who they are, how they feel and, above all, who’s to blame for their grievances.

What arouses people — what makes them feel validated — are Trump’s complaints that “we don’t win anymore,” and, to a lesser degree, Cruz’s promises to pull us “back from the abyss,” as he put it in January.

Something similar is happening with Bernie Sanders on the Democratic side — but in his case the scapegoat is Wall Street rather than the Muslims or undocumented immigrants who populate the demonologies of Trump and Cruz.

Kasich, to his credit, has refused to match their ugliest rhetoric — one reason, possibly, that he polls well with the more moderate November electorate.

Yet this has not helped him with overwhelmingly white doom-and-gloom GOP voters — 56 percent of whom told Pew that immigrants “burden” the country, and only 46 percent of whom said increasing racial and ethnic diversity makes America “a better place,” in contrast with 71 percent of Democrats.

In March, Rand re-surveyed the same people it polled in December; those GOP voters who thought the country was on the wrong track in the first poll were 40 percent less likely to support Kasich than Trump or Cruz, according to researcher Michael Pollard. Republican voters who thought the economy was getting worse were 45 percent less likely to support Kasich.

This, even though GOP voters identified Kasich as the candidate closest to them on the ideological spectrum: The Ohio governor scored right at the party’s midpoint, Trump well to the left of it and Cruz to the right.

At various times in our interview, Kasich faulted his opponents’ negativity, accusing them, a bit inelegantly, of driving the people “into the ditch.”

He flatters the voters. “Into the ditch” is the course they have chosen, and if an electoral apocalypse awaits Republicans in November, it will be of their own making.

Read more from Charles Lane’s archive, follow him on Twitter or subscribe to his updates on Facebook.