Cami Anderson, the superintendent of the Newark public school system who became a lightning rod in the debate over education reform in New Jersey and nationally, resigned on Monday, eight months before her contract was to expire.

An adviser and longtime friend to former Mayor Cory A. Booker and appointed by Gov. Chris Christie, Ms. Anderson had been hounded by protests from students, parents and local leaders for more than a year. She had feuded openly with the city’s populist new mayor, Ras J. Baraka, a former high school principal who was elected last year on a promise to return Newark — and its schools, which have been under state control for 20 years — to Newarkers.

Ms. Anderson was appointed in 2011, just as a $100 million grant from the Facebook founder Mark Zuckerberg had set up the long-troubled school district — the state’s largest, with some of the nation’s most disadvantaged children — to become a national model for change. Ms. Anderson, 43, used some of that money to establish merit-based pay in a teachers’ contract that was hailed even by national unions as a groundbreaking compromise.

She resisted the push by Mr. Booker, a Democrat who is now the state’s junior senator, and Mr. Christie, a Republican, to expand charter schools, fearing aloud that they drained motivated families and money from traditional schools. But she also alienated many parents with her reorganization plan, known as One Newark, which replaced the city’s tradition of neighborhood schools with a universal enrollment system that assigned students by lottery to traditional as well as charter schools. It resulted in school closings, mass firings of teachers and principals, and more students in charter schools, which aggravated complaints that Ms. Anderson was catering to wealthy ideologues with misguided ideas about how to improve urban education.