Plans for a new Port Authority Bus Terminal were on an encouraging pathway toward reality until Tuesday, when Andrew Cuomo suddenly reminded us that Chris Christie isn't the only bully around here who knows how to weaponize public funds.

An impudent and unhinged letter from the New York governor's surrogates was sent to the PA Board, demanding that Chairman John Degnan recuse himself from the planning phase, accusing him of "personal priorities," inflating the terminal cost to $10 billion, and using eminent domain for the project.

That's three falsehoods in just one letter - not a record for a governor, but we give Cuomo credit for trying.

The unofficial Jersey reaction should be a strategic yawn, because New Yorkers should know that any effort to undermine the PABT means they can forget about New Jersey's support to modernize the squalid LaGuardia Airport.

Cuomo's motives for such a juvenile gambit are unclear, though one can assume it is rooted in age-old conflicts between the states about project money and primacy and a desire to get Degnan, a superb advocate for New Jersey's interests, out of the equation.

That's not going to work. As recently as 23 days ago, Rep. Jerry Nadler - the chief signatory and tantrum-thrower in Tuesday's letter - agreed that the next step is for the board to approve a capital plan, one that will cost about $25 billion over 10 years and include makeovers for the PABT, LaGuardia, and Terminal A at Newark-Liberty.

Remember this: Among these "circles of hell" (to use Degnan's term), the decrepit bus depot was the only capital project that received unanimous approval from the fractious board, including every New York member.

It seems to elude their politicians, however, that a new PABT benefits everyone. It will have New York footprint, it will be built by New York labor, it will deliver New York tax revenue, it will bring consumers and investors to Nadler's constituency, and it will transport hundreds of thousands of New Jerseyans to New York jobs in a human environment, rather than through 66-year-old dungeon more suitable for vermin.

That seemed abundantly clear until Nadler's demented letter arrived.

"It's astounding to me that Nadler decided to fire this broad, insulting shot at both me and the process," Degnan said. "I don't understand it. There's got to be an explanation. Ask him."

We're still in the foothills here. We still don't know how much money in the Capital Plan will be earmarked for the terminal - executive director Pat Foye calls it "significant," but they haven't even decided on a design yet. There are many steps before they approve engineering plans, cost estimates, and board authorization for bonds and contracts.

Still, Foye emphasized, "We made that commitment (to funding the bus terminal), and there's no going back."

And the Board chair shall lead them. As Senate Majority Leader Loretta Weinberg and Sen. Bob Gordon (D-Bergen) pointed out, Degnan's career and professionalism are unimpeachable. And now that this spitting contest is entering a loopy political phase, it's worth noting that both Nadler and Cuomo have gone underground.

Until they resurface and apologize for slandering Degnan, we hope they'll take this unofficial New Jersey warning to heart: Should they choose to drag their heels on terminal project, they had better learn to live with having a third-world air strip on Flushing Bay symbolize the great Empire State.

Bookmark NJ.com/Opinion. Follow on Twitter @NJ_Opinion and find NJ.com Opinion on Facebook.