Mayor Eric Adams has only one strategy for the migrant crisis that has brought the city’s homeless-shelter population to six figures: wrangle billions from Washington.

This gambit will continue to fail, as it has for a year — and for two solid political reasons, from national Democrats’ perspective.

At best, federal aid would be pointless.

New York is a solidly Democratic state.

At worst, federal aid will make the problem worse — and more visible to national swing voters.

If the definition of crazy is doing — or saying — the same thing repeatedly and expecting a different result, Adams qualifies.

He was at it again last week: “New Yorkers have been left to deal with this crisis almost entirely on our own,” he said. “We are compelling Washington to help.”

But he ignores the fact New York helped make this crisis.

Yes, President Joe Biden has failed to secure the border, and Biden and Congress have failed to create — and enforce — a rational immigration and asylum policy.

But New York is the only city in the country bent on doing the impossible: giving every single person who arrives here, from anywhere in the world, for any reason, indefinite shelter.

“What we are doing is what you don’t see any other municipality doing,” the mayor said.

That’s because it makes no sense.

New York has long had an immigrant population, including people with no authorization to be in the country.

But immigrants always found their own (black-market) jobs and shelter, often renting a room in a cut-up Queens or Bronx apartment.

This was not optimal, but it worked.

What doesn’t work is the city of New York competing with tourists and business travelers to bid up the price of thousands of hotel rooms, to house an unlimited number of newcomers from four continents.

Adams hides behind the city’s “right to shelter” obligation.

But the state’s highest court has never ruled on the obligation’s basis: whether the state Constitution’s directive to aid the “needy” created a right to shelter.

Adams could challenge whether this supposed “right” applies to people with no ties to New York City, but he hasn’t.

Instead, he’s doing what New York did after 9/11, after the 2008 financial crisis, and during COVID: ask Washington for billions.

If you’re a White House insider, the obvious question is: What’s in it for President Biden?

What are New Yorkers going to do if they don’t like the cold shoulder, vote for Donald Trump?

On 9/11, New York had a Republican governor and mayor.

During the 2008 financial crisis and COVID, the city benefited from the fact that the president during each era, Barack Obama and Trump, had personal ties to the city. (Obama is a Columbia grad.)

Biden isn’t personally tied to New York, and he knows the state won’t be remotely in play next year.

Yes, last year, Lee Zeldin, a Trumpian Republican, came close to winning the governorship, and New York state lost the Democrats the House.

But these outcomes were because voters were fed up with state politicians (over crime and quality of life), not over national issues.

So there’s no political upside to sending billions to New York — but plenty of downsides.

An announcement that Washington will provide open-ended billions to New York to house migrants in midtown Manhattan will reverberate around the world — and encourage more people to cross the border.

Similarly, Adams has wanted the feds to house migrants on federal property in Brooklyn (Floyd Bennett Field) and Staten Island (Fort Wadsworth).

Over the weekend, though, the White House refused the Brooklyn site — flatly humiliating the governor, who made the request.

Does Adams really think the White House wants to send this message to would-be border crossers: Come to New York, the federal government has got a bed on a military base waiting for you!

The national narrative — including in swing states — would become: Biden’s promise to guarantee unlimited migrant housing in the most expensive city in the country, including directly on federal property, causes yet another surge at the border.

Plus, the city would actually run any shelter on federal properties — meaning Washington would relinquish control, even as it would retain responsibility, in the eyes of national voters, for any failure at the sites, from bad food to sexual assaults.

There’s a reason the White House is treating New York with contempt.

Politically, telling New York to drop dead isn’t just risk-free. It reduces political risk.

Nicole Gelinas is a contributing editor to the Manhattan Institute’s City Journal.