More than three years after Facebook founder Mark Zuckerberg committed $100 million toward remaking Newark's struggling schools, the district is engulfed in a dispute over proposed large-scale teacher layoffs that's threatening to derail wider reform efforts.

Nearly half the money has been invested in a 2012 teacher contract that was hailed by Gov. Chris Christie and the nation's top teacher's union official as an example of adversaries joining forces to rebuild a struggling urban school district. The contract, partially funded by the Facebook money, made Newark the state's first district to allow for teacher merit pay and peer reviews.

But the implementation of the contract, including a dispute over emphasizing teacher performance in determining layoffs, has devolved into a bitter fight between Superintendent Cami Anderson and teachers unions over the future of New Jersey's largest school district.

Newark's schools were brought under state control in 1995 following years of mismanagement, chronically low test scores and crumbling infrastructure in the city of 280,000, where the median household income is less than half the state's average. Zuckerberg was persuaded by then-Newark Mayor Cory Booker to invest in remaking the district, a donation announced in 2010 on "The Oprah Winfrey Show."

Since then, the contract's implementation has stalled, with both sides blaming the other for acting in bad faith. A recent request by Anderson for a waiver that would allow her to circumvent state tenure rules and base layoffs on a teacher's effectiveness rating along with years of service has provoked the ire of local teachers unions and American Federation of Teachers head Randi Weingarten.

According to the district's projections, about 30 percent of Newark's 3,200 teachers need to be laid off over the next three years to close a projected $100 million budget gap, while some new teachers will need to be hired in hard-to-staff subjects. Ruben Roberts, the executive director of community affairs and engagement for the district, says teacher layoffs are an inevitable consequence of bringing staffing levels in line with enrollment, which has declined from about 75,000 students in 2003 to about 36,000 in 2014.

"No one likes laying off teachers, nobody wants to, and in Newark, nobody has," Roberts said. "The position we're in now is due to the reluctance of past administrations to reduce the size of the workforce to mirror the shrinking of our footprint here in the district."

Anderson says performance-based layoffs are the only way to ensure that the majority of those let go are among the lowest-performing teachers. Without considering performance, Anderson argues, most layoffs would come from the pool of high performers.

"(Newark's school district) must address its fiscal crisis while increasing teacher quality," Anderson wrote in the waiver request. "The only way to do this is to be granted an equivalency to right size with quality alongside years of service in order to remain competitive and offer quality schooling options for all Newark families."

The layoffs are part of her wider "One Newark Plan," which calls for creating "100 excellent schools" by 2017 by transforming existing schools or creating new ones, expanding charter schools, downsizing the workforce in some areas and increasing it in others, and establishing districtwide frameworks for accountability and teacher and student evaluations.

The district has also been working to replace the traditional enrollment model in which students attend the public school closest to their home with universal enrollment, which allows families to use a central online gateway to research school options and submit an application with ranked preferences for both public and charter schools. Anderson says the plan has been developed with extensive community and stakeholder input, and she cites the 10,000 families that have signed up under open enrollment as proof that parents want better schools for their kids.

But union officials, some state lawmakers and hundreds of angry parents have blasted Anderson's waiver request as the latest example of her trying to implement changes with no community input while disregarding the contract she once endorsed. They argue that recently revised state tenure law allows for performance-based teacher dismissals. The state Senate recently approved a resolution calling Anderson's waiver request "an attempt to usurp the authority of the Legislature."

Weingarten wrote a recent open letter to Christie complaining that the "One Newark" plan is nothing more than a ploy to gut public education and replace experienced teachers with a cheaper, less experienced workforce drawn from programs like Teach for America, where Anderson was formerly an executive.

"This is a failure of management, a failure of fiscal stewardship and a failure of instructional leadership," Weingarten wrote. "Rather than deal with the fact that Newark students are suffering, school buildings are crumbling and staggering inequities persist, Superintendent Anderson would instead blame and mass fire the people who have devoted their lives to helping Newark's children."

Acrimony over the teacher layoff portion of the plan has reached a fever pitch, and much of the ire has been directed at Anderson, who was appointed in 2011 by Christie's former state Education Commissioner Christopher Cerf to reform the state-controlled district.

Anderson and her team argue that the state tenure law process is costly and lengthy to arbitrate and cannot be executed fast enough to keep pace with the growing financial crisis in the district and its low-performing schools.

Recent meetings of Newark's School Advisory Board -- an elected body that wields little decision-making power but has been pushing to regain local control of the schools -- have devolved into shouting matches where hundreds of parents and teachers wave anti-Anderson signs and call for her resignation. Anderson announced recently that she would no longer attend the meetings until the focus returned to discussing education.

Tamara Moore, whose five children are enrolled at Newton Street Elementary School, which is slated to close under Anderson's plan, showed up at a recent meeting with several hundred other parents with protest signs, including pink slips with Anderson's name on them.

"Generations of families went to Newton Street Elementary School. Now you mean to tell me that you're going to close the school, and you really don't care what's going to happen to these families and these children?" Moore said.

Christie recently reiterated his support for Anderson in his State of the State speech, crediting her with expanding early childhood enrollment and increasing graduation rates in Newark by 10 percent.

"Newark is leading the conversation in making sure every kid -- those who are behind, those who are ahead and those who have special education needs -- are lifted up," Christie said. "Under Cami Anderson, every kid means every kid."

Kimberly Baxter McLain, who heads the Foundation for Newark's Future, which administers the Zuckerberg donation, said she's satisfied with how the investment is going. About $80 million of the challenge grant has been invested so far -- $48.5 million of it in the teacher contract, she said.

"Overall, where people may disagree on how we get there, I think people are supportive of the same vision, which is that every school is made excellent for our children," McLain said.