If Mayor Adams is going to start filing Hail Mary lawsuits over the city’s migrant crisis, why stop at a few bus companies?

Go big, sir: Sue the feds!

It may be tough to make a case that won’t get kicked right out of court, but at least it’ll put New York City’s plight in the national headlines.

After all, the $700 million lawsuit against the bus companies transporting migrants from Texas to the Big Apple is self-evidently hopeless.

It’s based on a state law that says: “Any person who knowingly brings, or causes to be brought a needy person from out of state into this state for the purpose of making him a public charge . . . shall be obligated to convey such person out of state or support him at his own expense.”

The bus companies need only show that they’re not out to make any “asylum seeker” a public charge; they’re just moving people they’re paid to move: That’s what charter companies do.

The city might have better luck suing the folks chartering the buses — except that means going after not just Texas Gov. Greg Abbott, but also Catholic Charities and the other nonprofits that do most of the chartering, which would make for terrible headlines.

Even then, the charities (and Abbott!) can argue that their purpose is simply to get the migrants where they want to go — it’s not their fault if that’s New York.

So get the Corporation Counsel’s Office busy figuring out how to sue the federal government, which after all is to blame, since Uncle Sam is the one “paroling” millions of illegal border-crossers who transparently have no legitimate case for asylum in the United States — and, the suit would show, the one making arbitrary and unfair decisions about what funding it offers localities who have to deal with the disastrous consequences.

Heck, it could be a joint lawsuit with hard-hit towns like El Paso; it might even be worth getting Abbott to join in (it’s far easier for states than cities to sue the feds), since Gov. Hochul is so cautious about . . . everything.

And if you absolutely must have a New York state official, Attorney General Tish James has a long history of jumping aboard longshot lawsuits dating back at least to her time as New York City public advocate.

The suit doesn’t even have to name President Biden to put pressure on him, and his re-election year is the last time he’ll feel any political pressure at all.

Almost two years of Adams sniping at Biden, along with fruitless sit-downs with Homeland Security boss Alejandro Mayorkas and assorted White House flunkies, has gotten the city bupkis.

All the mayor himself has gotten is 1) kicked off Biden’s campaign and 2) a federal corruption investigation.

Sue the feds, Eric: Nothing else is working anyway.