Progressives are on the verge of killing one of the Big Apple’s biggest and most controversial affordable housing programs, potentially nixing the construction of thousands of new rent-stabilized apartments as rents soar across the city.

Efforts to extend or overhaul the 421-a program have stalled in Albany amid fierce opposition from lefties and ineffective pushback from City Hall’s dysfunctional statehouse operation, which has failed to reach out to key lawmakers.

“This is all politics. What’s going on here is the far left wants to trade it for [limiting evictions] and you’ve got people facing primaries who would prefer that nothing happen,” said one veteran Albany operative.

The 421-a program, set to expire in June, provides developers with city property tax abatements worth an estimated $1.8 billion in exchange for agreeing to limit and regulate the rents on a portion of the apartments in the new buildings they erect.

“In the last decade, about 8,000 affordable units were built using 421 with no subsidy,” said Vicki Been, the city’s former commissioner and deputy mayor of housing who now runs the Furman Center at New York University. “And that’s a lot when you think about how hard it is to build new apartments, that’s a really important source.”

All told, 421-a either partially or completely funded 4,030 of the 4,279 newly rent-stabilized apartments in New York City in 2020, figures from the Rent Guidelines Board show.

Not only that, Been added, research set to be published by the Furman Center this summer shows new affordable apartments bankrolled by 421-a are built in wealthy areas, where median incomes are more than $80,000 annually.

The units built using direct subsidies are placed in poorer areas, where incomes are just $48,000 on average, because officials get better bang for their buck.

“They are built in neighborhoods that are almost twice the median income of the neighborhoods where other affordable housing is being built,” Been said. “They’re getting people into the neighborhoods that the subsidized housing can’t afford to build in.”

Mayor Adams sounded resigned when pressed about the program’s fate on Friday.

“My job is to present a case. They deliberate and they come back,” Hizzoner told reporters. “I think we presented a strong case on why we need to have an extension of 421-a.”

But, he added, “I cannot say that we’re not going to do what we have to do, based on what happens at Albany or the federal government. We need to continue building the city. I’m hoping that they look at a potential extension of 421-a [of] at least a year, but it’s up to them.”

The program’s premise is simple — create affordable housing via New York City’s broken property tax system, which hits new rentals hard, while providing discounts to homeowners in neighborhoods where property values are soaring.

It gives developers tax breaks in exchange for setting aside newly-built apartments for qualifying lower, middle or upper-middle class incomes. Those units are put in rent stabilization, so future hikes are capped by the Rent Guidelines Board.

But progressives have long had the program in their sights, angered over its very structure and provisions that allow developers to set rents for some of the apartments for households with incomes that exceed the city average by as much as 30%.

That means a family of three making $156,000 annually can qualify for an apartment — which would potentially cost $3,900 a month for a two-bedroom apartment.

“421-a has long outlived its usefulness and should have been repealed,” said one critic, state Sen. John Liu (D-Queens).

Another Democratic honcho in the upper chamber, state Sen. Liz Kreuger, claimed in a statement the current program “mostly subsidizes market-rate apartments and luxury apartments.”

Gov. Hochul included an overhaul of 421-a in her initial budget proposal that would have capped eligibility at lower levels: A family of three could qualify if they made $108,000 and the rent would be lower too — $2,700 a month for a two-bedroom.

Adams’ Albany operation did not mount a concerted campaign to back the overhaul as part of the budget passed in April — or as the session closes.  

Just two of 16 key Democratic lawmakers reached by The Post — who either sit on relevant committees or are in leadership — were contacted by Adams or city lobbyists over the future of the billion-dollar program before Hizzoner’s Albany trip last week.

“It’s the least muscular legislative operation I’ve seen in my time by a city mayor,” said one veteran Democratic state senator.

Even still, Albany operatives said they weren’t sure an Albany operation hitting on all cylinders would be able to make a difference because of fears among Democratic lawmakers of being accused of aiding developers as the summer primaries approach.

“The mayor’s been slow on pulling together a team that knows how to operate in Albany,” said the veteran lobbyist. “On this issue, I don’t think it would make a difference.”  

Meanwhile, lefties like City Comptroller Brad Lander, leaped into the vacuum and campaigned against Hochul’s proposal by arguing it was too expensive and deferential to developers.

Instead, Lander argued, state lawmakers should let the program expire and embark on an overhaul of the property tax system that treats rentals more fairly, attempts at which have repeatedly failed.

Been served on the last property tax overhaul commission, which concluded in 2020 and issued recommendations that have since gone nowhere.

“I was on that commission, I can tell you how hard this would be,” she said, before adding about the looming lapse in housing tax abatements: “It’s discouraging, it’s just not clear what plan B is here.”

Additional reporting by Bernadette Hogan