Donald Trump is celebrating his fake “complete exoneration” by pledging anew to throw 20 million people off their Obamacare coverage. Is this guy politically stupid, or what?

What a gift for the Democrats, who recently scored their biggest House midterm sweep since 1974 by decimating the GOP on health care. If Trump truly intends to revive the issue in 2020 by taking yet another crack at Obamacare (which, after nine years, is more popular than ever), Democrats are only too happy to oblige him. Senate Republicans know that he’s nuts to do so. They have no appetite to launch another kill-Obamacare crusade, having failed in 2017, and having failed for nine years to come up with a replacement plan. But, as always, they’d rather quake in their boots than tell Trump the truth: That an umpteenth assault on the health law will imperil him and them in 2020.

They prefer to fret in private. Kevin McCarthy, the House Republican leader, has reportedly blamed the 2018 blue wave on the Trump-GOP’s efforts to gut Obamacare — with good reason. Because voters trust the Democrats on health care by a decisive margin, health care was the top-ranked issue in the midterms, and of those voters who ranked it highest, 75 percent chose Democratic candidates. Yet Trump still seems to think he has powers of persuasion beyond his base.

I’m frankly puzzled: If he couldn’t kill Obamacare when the GOP held the White House and both congressional chambers, why does he think he can kill it — and replace it with something he calls “spectacular” — when one of the chambers is Democratic? But that’s a rational question, and we live in irrational times. Trump wants Senate Republicans to craft a replacement plan, while Senate Republicans want Trump to do it. Which explains why Mick Mulvaney, Trump’s acting chief of staff, and John Barrasso, the third-ranking Senate GOPer, were so deceptive and evasive on the Sunday shows.

Mulvaney told ABC News that if Obamacare is killed, a Republican replacement plan would guarantee that everyone currently covered by health reform — including young people up to age 26, and the tens of millions of people with preexisting conditions — would be fully protected just as they are now. That is a lie. Every GOP draft proposal floated during this decade has imperiled people with preexisting conditions, by allowing insurance companies to charge them higher premiums for coverage. Meanwhile, Trump has endorsed a federal lawsuit, launched by attorney generals in 20 red states, that seeks to repeal Obamacare in its entirety — including the protections for people with preexisting conditions, a category that includes 27 percent of all non-elderly adults.

So where’s the Republican replacement plan that would magically make everything OK, the plan that would provide the same protections as Obamacare but do them better? John Barrasso of Wyoming, the number three Senate Republican, was asked about that — multiple times yesterday — on “Meet the Press.” Watch him writhe, if that’s your preference (it’s not fun to carry water for Trump), but here’s the gist of how it went:

Chuck Todd: “It was in 2009 that we began the debate. It’s 2019. You guys have been talking about a plan to protect preexisting conditions for 10 years. And you haven’t been able to come up with one.” So what’s your plan?

Barrasso: Obamacare “has failed to keep its promises…This is on the American people’s minds.”

Todd: “Should the American people expect an actual health care plan alternative from the Republican party this year?”

Barrasso: “The American people should expect to not have to be burdened” by Obamacare.

Todd: “A plan. Will we see a new plan from the Republican party about what their alternative is?”

Barrasso: “I’ve been working on a plan since the day I got to the Senate.”

Todd (with the punchline): You’ve been in the Senate for 12 years.

That last exchange tells the tale. Health care is simply not what Republicans do. Their brand is to slash taxes for the rich, crater the deficit, and signal national security weakness to the Russians. It’s impossible to know whether Trump truly believes that erasing Obamacare’s protections will rebrand the GOP as “the party of health care” (his words), or whether he’s just feeling his “exoneration” oats and playing offense for a few news cycles before finding a new toy.

Republicans on the ballot in 2020 had better hope it’s the latter.

Dick Polman is the national political columnist at WHYY in Philadelphia and a “Writer in Residence” at the University of Pennsylvania. Email him at dickpolman7@gmail.com.