The question for Donald Trump is not whether he can beat Joe Biden. It is whether he can beat Joe Biden, an epidemic, a recession, and a few swing voters who just may have had enough of Captain Chaos.

Team Trump should be worried.

Republicans will nod their heads and pump their fists when Trump unloads both 12-gauge barrels on Biden, charging that he is senile, fragile, doddering, weak, confused, unsteady, unreliable, and at the center of a family network of rapacious political profiteering. But don’t expect that to be a knockout punch, even if you think it should be — Republicans are not Trump’s problem: Democrats and independents are.

All Biden really has to do is mend fences with the Sanders gang. Trump has a steeper hill to climb. In 2016, he won critical victories in Florida, Pennsylvania, Michigan and Wisconsin — but in none of those states did he break 50 percent. Trump’s margin of error is tiny.

The line that Trump is sure to deploy against Biden already has been tried in the primary — and Trump should take note: It did not work, in spite of the best efforts of Sanders’ surrogates who are every bit as vicious as Trump can be. Charging that Biden is senescent did not work on Democrats in Michigan or Minnesota, and it is not working in Pennsylvania, where Biden leads Sanders by 25 points in the polls — and where he leads Trump by 4.

Complaining about Biden’s gaffes is like complaining about Trump’s spelling or his adultery — it’s nobody’s news flash.

Biden’s remarkable comeback saw him ruthlessly push out every significant opponent save Sanders and then face off with the socialist from Vermont from Brooklyn and beat him like a rented mule.

And even if Biden is personally weak, the machine for which he serves as a mascot is as powerful as ever — and it will be even more powerful once the Sanders faction has remembered that it hates Trump more than it resents the DNC. The usual eleven nobodies on Twitter may make a big noise about abstaining rather than compromise with Biden, but Trump would be foolish to bet his re-election on a lucky fit of socialist pique.

Biden is running strong with African Americans and thoroughly beat Sanders among new Democratic voters, the ones who voted in the 2020 primary but not in the 2016 primary. Biden is going to have Buttigieg’s voters behind him, and Klobuchar’s, and probably Warren’s and Sanders’, too — along with Michael Bloomberg’s money.

What does Trump have?

Trump has spent much of his presidency boasting about high share prices and low unemployment. That was before the stock market tanked 20 percent in response to the Wuhan plague and the Trump administration’s incompetent response to it, including the president’s error-laden Wednesday evening speech that sent markets plunging again on Thursday morning. Trump’s inability to get the basic details right — no, the insurance companies have not agreed to waive copays for coronavirus treatment, no, we haven’t suspended all air travel from Europe — undercuts his standing to paint Biden as confused and out-of-the-loop.

Economic growth was already short of the steady 3 percent growth Trump promised and is now being hurt by the disruption of worldwide supply chains and by tanking travel, trade and tourism. As of March 11, even the traditionally right-leaning Rasmussen poll reports that his national disapproval rating is 52 percent, compared to 47 percent in favor.

The coronavirus is a new kind of political problem for Trump, one he cannot bully into submission the way he did his fellow Republicans or buy off with taxpayer money the way he did with farmers hurt by his trade war with China. It is a real test of his executive competence, and, so far, he has been found wanting.

If it should get bad enough to cause a serious economic contraction — which is far from unthinkable — then Trump is going to have to come up with something better than what his apologists are offering right now: “The buck stops elsewhere.”

Kevin D. Williamson is the author of “The Smallest Minority: Independent Thinking in the Age of Mob Politics.”