President Donald Trump may be a shrewd negotiator, but holding the new Hudson River rail tunnel hostage isn’t particularly smart — it’s petty.

At least, it sure looks like Team Trump is holding up the tunnel’s funding as part of unrelated battles with Democrats.

And if it doesn’t release $200 million of the cash by Friday, work on the tunnel must come to a full stop, laying off a thousand workers and saddling the $16 billion project with needless huge, added costs in delays and penalties.

Perhaps worst, it would delay a key piece of the local transportation network that’s needed yesterday — a hit to the regional and national economies.

On Monday, the Gateway Development Commission, which is overseeing the work, sued to have the money released;  New York and New Jersey filed their own suit the next day.

But litigation won’t move the ball in time to prevent the Friday stoppage: The president will have to overrule his minions to do that.

The new tunnel under the Hudson will serve trains running between New Jersey and New York and allow uninterrupted service while the existing tunnel — which is 116 years old and badly damaged, but still handles 200,000 passenger trips a day — is repaired.

Once finished, the two tunnels would double the capacity, and reliability, of train service across the river. Amen to that.

Congress has already funded the project, and the job’s been underway for two years; $1 billion is already out the door.

So halting work now is nuts.

Yet in October, Trump threatened to kill the project entirely, claiming the Democrats’ government shutdown was holding up a review of the project needed to ensure it contained no illegal DEI measures.

That shutdown is over, yet Trump folks have a new excuse: They now say they’ll restore funding only if Democrats fully fund the Department of Homeland Security.

OK: Dems are playing #Resistance blackmail by refusing to greenlight a DHS budget without changes to immigration-law enforcement — which is also nuts, since ICE, the focus of their ire, is already funded, so they’re really threatening to slam TSA operations, emergency funding through FEMA, the Coast Guard, etc.

And their demands aren’t practical, beyond the one that Team Trump has already OK’d: body cameras for DHS agents.

Fact is, Trump is better off letting the Dems have their fit; they’ll come to their senses soon enough, when airports clog or disaster-relief funds stall.

Whereas if the tunnel project is halted, most of the Trump-hating media will blame him, not Democrats.

And a project that the prez could champion — and claim at least partial credit for — would be stalled.

It’s a lose-lose for everyone. Where’s the art of the deal in that?