Mayor de Blasio snubbed President Trump last week, refusing to attend a mayors’ meet-up on infrastructure after the Trump White House demanded more information on sanctuary cities. De Blasio said he slighted the president because “the only thing he understands is force and resoluteness.” But if you’re going to fight power with power, you’ve got to have . . . power.

De Blasio has little.

De Blasio was one of several big-city mayors to skip the White House meeting. But of those, he has the most to lose by angering Trump.

New Orleans Mayor Mitch Landrieu, who led the resisters, is leaving office in May. Politically, Landrieu can afford to risk making things a little bit difficult for his successor.

Louisiana has two Republican senators to protect its interests in a bill for roads, bridges and floodwater protection, and a Democratic governor who’ll look out for the interests of the state’s biggest city.

Chicago Mayor Rahm Emanuel also refused to attend. But Illinois has a Republican governor, one who will need to show he can bring federal money home to the state to keep his seat this fall.

New York, on the other hand, has a Democratic governor — one who already can’t get along with de Blasio. Cuomo may seize this new and deeper rift between de Blasio and Trump as an opportunity to cut Gotham out of its fair share of transit and road funding.

Cuomo has a financial motive: he needs billions for his favored projects outside of the five boroughs, from the $4 billion Tappan Zee Bridge project, mostly built but still not paid for, to a tunnel he keeps promising between Long Island and Connecticut.

And there may be less money to fight over: Sen. Chuck Schumer’s negotiating prowess looks less formidable than it did two weeks ago, before he shut the government down over the Dreamers and promptly reopened it once he realized it wasn’t a winning stance.

Immigration is complicated — and it’s a mistake for de Blasio to tie it, politically, to transit and highway spending, just as it was for Schumer to tie it to a temporary budget measure.

New York also has little physical advantage. New Orleans and Chicago have their road, bridge and transit needs. But none is in New York’s situation, needing billions from the feds to expand its subway.

Chicago, with a stagnant population, doesn’t face the pressures of a record number of residents and workers that New York does. (New Orleans, though it’s creeping back toward its pre-Katrina population, also has plenty of room to grow.)

Then, there’s fiscal weakness. The first phase of the Second Avenue Subway, costing $4.4 billion, got a $1.3 billion grant from the federal government, or 30 percent. But a leaked document last week purporting to list the White House’s transportation priorities would cap future such investments at 20 percent per project. That would imperil the next three stops of the Second Avenue Subway.

That’s especially a problem when much of New York’s money from any big transportation bill — at least $6 billion — must go to a new Hudson River tunnel, to replace the 108-year-old conduit encrusted with corrosive salt water.

New York would benefit from the new tunnel. But crammed-in subway riders don’t directly benefit, as they would from more progress on Second Avenue.

Finally, there’s the mayor’s future. De Blasio fancies himself a national leader. But the unpalatable fact is that whoever successfully takes on Trump will have to win over some of Trump’s voters. One doesn’t do that by publicly humiliating the president.

De Blasio could have shown strength by attending the meeting — and making a forceful case, to the president’s face, that New York needs a national immigration law that resolves the fate of people right now relying on vague “sanctuary city” protections.

As it is, though, he didn’t help undocumented immigrants, and he certainly didn’t help all New Yorkers’ prospects for getting around.

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