Two-thirds of New Yorkers think Gov. Andrew Cuomo is doing a bad job with the subways, according to a new Quinnipiac poll. But this dismal showing hasn’t spurred Cuomo to change his ways when it comes to an invisible part of how transit works: the money.

The state is now forcing even more debt onto the MTA for a project that won’t give commuters a payoff.

Cuomo is famous for his infrastructure projects, and one of his favorites is Moynihan Station. He’s transforming the old Post Office on Eighth Avenue across from Penn Station into, as he said last year, “a world-class 21st-century transportation hub.” It’ll be Amtrak’s new home and will have waiting areas for LIRR passengers, with shopping, restaurants and office space.

LIRR riders get some benefit from this — better access to platforms (a part of the project that is already finished, and is nice). Other than that, the biggest change they’ll see is the extra space to wait or buy tickets — a hall bigger than Grand Central.

These changes aren’t worth half a billion dollars to the MTA. People don’t show up for LIRR trains hours early to wait around, and they can buy their tickets online.

Indeed, the governor has never publicly stated that the MTA would have to shoulder the burden of nearly a third of this $1.9 billion project’s cost (up from a $1.6 billion estimate last year).

Last year, the plan was that private developers would put up $600 million for the office and retail space. Albany, through its Empire State Development Corp., would put up $570 million. The MTA, through the LIRR, would pay a small portion of the remaining $425 million. Amtrak, the Port Authority and other mysterious sources would take up the rest.

Now it turns out the state will get almost all of its $570 million from . . . the MTA.

Last week, the ESDC prepared to borrow $537 million from the federal government for the project. Developers are supposed to repay the debt with a portion of their office and retail rents at the station.

But what if they can’t? Development doesn’t always work out as planned. Office towers can have a hard time finding tenants. It’s impossible to predict what the retail market, already saturated, might look like in a few years’ time.

So lenders — in this case the feds — want some other guarantee. At Hudson Yards, the city made $358.8 million in interest payments on more than $2 billion in debt over the past decade to make up for developer shortfalls on a similar project.

At least until 2033, as the Fitch Ratings analyst pointed out last week, the MTA will “support” 100 percent of the interest and principal repayments on the state’s Moynihan debt if the retail and office space doesn’t pay off as planned.

“Absent the MTA support . . . uncertainty at this stage of the project would preclude the [federal] loan from achieving an investment-grade rating,” the bond analysts noted. “This transaction is unique.”

In the context of the MTA’s existing debt payments — $2.6 billion a year — another few tens of millions in annual interest costs won’t bankrupt it (probably). But we’re in an emergency environment: The MTA is supposed to be dedicating all of its scarce money to critical projects like subway-signal upgrades and more train cars.

Taking on a third of the financial responsibility of building a “home” for someone else (Amtrak) shouldn’t be on the list.

This arcane financial shenanigan also bodes poorly for Cuomo’s commitment to give the MTA an additional $1 billion next year to help cover a shortfall in its $32.5 billion long-term investment plan.

On one hand, if this promise holds true, the state will give the MTA more money. On the other, the state is already taking away more than half of that “extra” $1 billion through this convoluted transaction.

The MTA has a new chairman, Joe Lhota — whose main job should be to stand up to Cuomo when it comes to these things. If the governor wants a new “train hall,” fine. But the state should find a way to pay for it without taking money from subway and commuter-rail riders.

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