Despite heightened demand, the charter school movement in New York is fighting for crumbs in the final hours of state budget negotiations, with no new school slots available for the Big Apple, which is left to pick over the bones of charter schools that closed.

State lawmakers and an embattled Gov. Andrew Cuomo are blocking a bid to significantly expand access to charter schools despite pent-up demand from parents seeking a quality education for their kids, critics charge and sources confirm.

The charter school movement faces an uphill battle to lift the legal cap on opening more of the popular alternatively run schools as state leaders work through the weekend to formalize a budget, sources close to the negotiations said Friday.

Democratic lawmakers — aligned with the anti-charter school teachers union — are resisting any lifting of the charter cap, which is set at 460 statewide, with 290 of those slots set aside for New York City.

The Big Apple has already hit the cap.

There are 92 unused charters left for the rest of the state but they can’t be used in the city — where the demand is — without a change in state law, which appears unlikely, sources said.

Instead, negotiations largely center on a much more modest proposal: reauthorizing 20 so-called “zombie” licenses to new charter school applicants. These currently unused charter licenses were issued for charter schools that closed, for example.

“It’s ridiculous that the people elected to represent us don’t want a quality education for children in low-income communities,” said parent Leslie Thach, whose son, Sebastian, is a first grader at the Boys Prep charter school in The Bronx.

“It’s sad that parents have to fight for this. It’s very disappointing. It should be a given.”

Boys Prep has a strong science program and offers regular extracurricular programs not available at her son’s zoned public school, Thach said.

The political environment has become more hostile to the once-booming charter school sector ever since Bill de Blasio, who has fought charter school expansion, replaced charter school champion Mike Bloomberg as New York City mayor.

Meanwhile, last year, teachers union-friendly Democrats won control of the state Senate in addition to the Assembly, replacing pro-charter Republican allies.

Now both houses of the state Legislature are more aligned with the teachers union.

The unions oppose charter schools in part because they’re privately managed and non-unionized. They and other education advocates also claim charter schools divert funds and students from traditional public schools.

But studies have shown that students in charter schools, which typically have a more structured administration and often a longer school day and year, tend to outperform those in neighboring traditional public schools on the state’s standardized exams.

The number of parents who want to enroll their children in charter schools greatly exceeds the demand because of the cap.

Even one-time staunch charter ally Gov. Cuomo — weakened by nursing home and sexual harassment scandals — has tempered his support.

His initial budget plan introduced in January just proposed re-issuing the unused, zombie licenses and did not call for lifting the charter school cap to allow for robust expansion to meet parental demand.

The Assembly’s top point person on education confirmed that raising the charter school cap is out of the question.

“My members by and large want the charter school cap to stay where it is. We weren’t behind the acceptance of charter schools to begin with. There are limits and we should stick to those limits,” said Assembly Education Committee Chairman Michael Benedetto (D-Bronx), a retired public school teacher.

The United Federation of Teachers said Friday it opposes any expansion of charter schools.

“We must level the playing field with charter schools. New York charter schools demand an ever-larger share of public school dollars, resources and facilities, yet they support fewer high-need students than our public schools and they do not meet the same standards of transparency and accountability,” the UFT said in a statement.

“We must hold charter schools to a basic level of accountability for how they use tax-payer dollars, and we must keep the charter school cap in place and avoid bringing back `zombie charters that could cost NYC $160 million.”

Cuomo’s office and senators had no immediate comment.