Charter schools are a mainstay in New Jersey's poorest cities, offering students alternatives to struggling public schools.

But as new publicly funded charters try to bring unconventional teaching methods to wealthy suburbs with high-performing public schools, they're running into legal tussles.

Some traditional public schools are objecting to upstarts that would siphon off students and money from their programs. They're fighting the charters off with technical legal arguments.

This summer, two suburban charter schools preliminarily approved to open in September have been scuttled - one thanks to a legal challenge by local public schools. The opening of a third is uncertain after the local school board filed a lawsuit to block it.

Derrell Bradford, executive director of the school-choice advocacy group Excellent Education for Everyone, said it's "a more sophisticated resistance than they would encounter in the hood."

Hemant Marathe, president of the West Windsor-Plainsboro Board of Education, one of three districts that could lose students to Princeton International Academy Charter School, said his community doesn't need a school that specializes in immersion learning of Mandarin. The district already teaches the language starting in fourth grade.

"We see the charter school as an elite school that is very specialized," said Marathe, the president of a software company.

Charter schools took off across the country in the 1990s as places where educators could try new teaching methods and offer competition to regular public schools.

Traditional districts in New Jersey are required to send the charter schools 90 percent of the money per student that the regular school spends, plus provide transportation to charter students.

While there are some suburban charters already, including one in Princeton, most are in places where the schools aren't meeting state educational standards. Half of New Jersey's charters are in just four cities: Camden, Jersey City, Newark, and Trenton.

The verdict on their academic results is mixed, but charters have exposed inner-city children to new opportunities. At Camden's D.U.E. Season school, the curriculum includes piano lessons and dance.

The feeling that public schools can do better isn't confined to cities.

Parker Block said he and others in the Princeton area have noticed that several public schools in other well-off suburbs around the country are offering immersion language programs. He said education officials in the successful public schools aren't receptive to suggestions to add bold new programs.

They founded Princeton International, specializing in teaching Mandarin. It received preliminary approval early this year to operate starting in September. About 300 students tried to enroll for a school with room for 170 students in kindergarten and the first and second grades.

The school picked a home in the former high school building on the grounds of now-closed St. Joseph's Seminary in Plainsboro.

But in May, officials learned they would need a zoning variance to put a new school there.

Just before the July 7 hearing, a lawyer for the Princeton, West Windsor-Plainsboro, and South Brunswick School Districts pointed out that the legal advertisement for the hearing neglected to include the hours of the Plainsboro zoning office.

The zoning board delayed the hearing, the state deadline for a July 15 approval passed, and the school won't open this fall.

"The only reason why we didn't open in September is because of a frivolous legal challenge," Block said, adding they would try again next year. "These are provincial, small-minded individuals who are playing politics with our children's future."

West Windsor-Plainsboro's Marathe said the technical problem wasn't the fault of the public schools. "They would like to blame everybody else," he said.

Another school, Trillium Charter School in Flemington, scuttled its planned opening this fall for a different reason.

While it had enough students enrolled, the state said not enough of them were from three designated sending districts.

Trillium contends the state Education Department misinterpreted a law when it found the school not to be in compliance.

It's not clear whether Hatikvah International Charter School in East Brunswick, which plans to offer immersion in the Hebrew language, will open.

The East Brunswick school board took legal steps this month to block the opening, saying the school did not have enough students to open. The charter disputes that claim.

School district lawyer Matthew Giacobbe said the Board of Education was trying to halt the school because it didn't want taxpayers' money to go to an entity not legally entitled to it.