President Trump has backed off his threat to bypass Congress by declaring a national emergency to build his wall. Meanwhile, Gov. Andrew Cuomo is effectively seizing emergency powers to end-run the MTA board with his L-train repair plan.

And they call Trump dictatorial?

On Thursday, the MTA said it’s going ahead with the gov’s plan to make critical repairs to the tunnel without the previously scheduled 15-month total shutdown.

That preempts what had been an expected vote Thursday by the MTA board, some of whose members have raised concerns about the new plan. Now the agency says no vote’s needed after all, because it doesn’t expect the drastic change of plan to hike costs.

Which, as The Post reported Saturday, infuriated some of the board: “We spent three to four hours in an emergency board meeting,” one member, Andrew Albert, fumed. “Obviously, this was all for naught.”

Board members could sue over the dubious move — but even those appointed by Mayor Bill de Blasio have to fear the gov, since they have other interests he can threaten. (Nice nonprofit you have there; what a shame if its funding got cut off …)

Yes, the new approach devised by Cuomo’s outside experts may well turn out to be safe, efficient and the best way forward. So why the gov’s goonish refusal to allow normal scrutiny?

In fact, Cuomo’s allergy to oversight led to the Buffalo Billion scandals that sent several of his close associates to prison. A closer review of those contracts before they got the go-ahead might’ve prevented the corruption that ensued. Yet Cuomo hates the idea of returning pre-contract review authority to the state comptroller.

Heck, the MTA itself could’ve used more oversight of such megaprojects as the $11 billion East Side Access (plagued by huge cost overruns and delays) and the Second Avenue Subway — both of which wound up sucking up MTA resources and so contributed to the deterioration of the subway system.

Meanwhile, the gov wants even more power over the transit agency, via legislation to let him pick a majority of board members. (His appointees now get just six out of 14 votes.) Why bother, if he’s only going to bully and bypass the board anyway?

Cuomo may detest having boards or outside reviewers vet his ideas. But the record shows that New Yorkers are at risk whenever he gets away with tossing transparency.