A key portion of Mayor de Blasio’s $24 billion public housing rescue plan has stalled, according to the Citizens Budget Commission — blocked by fellow liberals who oppose private development on publicly owned land.

City Hall hoped to score as much as $2 billion in repair money through deals that would put new housing towers with market-rate and affordable apartments on the Housing Authority’s land, only to hit a brick wall from anti-development pols.

“It’s not just that they’re opposing these projects, they’re opposing a lot of these project without presenting any reasonable alternative to raise the cash,” Sean Campion, a housing expert at the Citizens Budget Commission. “The longer they oppose these projects, the more NYCHA’s apartments deteriorate and the more expensive it becomes to fix them.”

De Blasio laid out the ambitious infill development goal in December as his administration labored to prevent a total federal takeover of the embattled agency, swamped by lead and living condition scandals detailed in a bombshell June 2018 lawsuit filed by US prosecutors in Manhattan.

It called for the partial privatization of a third of NYCHA’s units, selling development and air rights owned by the authority and for the infill projects to put a $24 billion dent in the authority’s daunting $38 billion repair bill.

But NYCHA’s half-dozen infill development proposals have gone nowhere over the intervening months, the CBC found.

It found that the proposals for Cooper Park and Wyckoff Gardens in Brooklyn and the La Guardia Houses, Harborview Terrace and Holmes Towers in Manhattan all “appeared stalled.”

The loudest and most organized opposition to the infill plans has targeted two of the longest gestating projects — Harborview and Holmes Towers.

That has come from local residents and the borough’s leading liberal Democrats, like Borough President Gale Brewer, who have offered a litany of objections to the projects — from concerns about the development process, to lost parking and playgrounds, to the shadows the building might cast.

“We know that NYCHA needs the funds but I’m a believer that the [zoning] process can give NYCHA want it needs,” said Brewer, who challenged the Holmes project in court.

“At least have a discussion, we might end up with more money,” she added. “There’s no public discussion of it. That’s all we’re saying is having a public discussion.”

NYCHA scrapped its Holmes Towers plans following Brewer’s lawsuit but said that the project would likely return with even more market-rate housing to generate more cash for the money-strapped authority.

The authority’s former interim chairwoman, Sanitation Commissioner Kathryn Garcia, also said in April the agency was eyeing adding market-rate housing to the Harborview project, too.

Neither the agency or City Hall have released new designs for either site yet — and its most recent proposal, at the Fulton Houses, has also run into opposition.

NYCHA did not comment Wednesday on the status of the half-dozen projects or the CBC’s assessment of the delays.

“NYCHA 2.0 is the best and only plan to preserve public housing in New York City for generations to come,” an agency spokesman said in a statement.