One of New York's top school policymakers called Monday for potentially revamping a controversial law that allows student scores on Common Core tests to count for as much as half of teachers' and principals' job evaluations.

Merryl Tisch, chancellor of the state Board of Regents, told about 500 school board members attending a state convention in Manhattan that the toughened law, pushed through the legislature in April by Gov. Andrew M. Cuomo, is "full of problems."

The chancellor said lawmakers should "reopen" a section of the law that increases to about 50 percent the maximum weight that local school districts can assign to so-called "growth" scores in judging teachers' classroom performance. Such scores are based on student performance on English language arts and math assessments, and are generated by a complex formula that many analysts consider statistically unstable.

The state's original teacher-evaluation law, adopted in 2010, limited the weight of growth scores to 20 percent of teachers' overall ratings.

State Education Commissioner MaryEllen Elia, who reports to Tisch and the Regents board, is scheduled to review the evaluation system and recommend potential changes -- a process expected to take at least two months. Elia, who also spoke at the convention, confirmed that her review would address the 50 percent weighting, among other issues, but declined to express an opinion on the subject.

Tisch, once an ardent proponent of more rigorous testing and teacher evaluations based on Common Core standards, also conceded during a panel discussion that she and other state leaders tried in 2010 to push too many reforms too fast.

"If it could be done over," Tisch said, the state should not have tried to put stricter teacher evaluations in place at the same time that it approved national Common Core academic standards. Those standards are the underpinning for curricula in New York and most other states, though such curricula are under widespread review.

New York State won nearly $700 million in federal Race to the Top incentives in support of its school reform efforts. However, the push for tougher testing and job evaluations drew growing resistance from teacher unions and parents, who say the combination places undue pressure on students and teachers.

In April, parents pulled more than 200,000 students in grades three through eight out of state tests -- the largest boycott of its type in the nation. More than 70,000 students opted out in Nassau and Suffolk counties alone.

Tisch's remarks drew repeated applause from delegates attending the New York State School Boards Association's three-day convention. Some, however, voiced skepticism that the state's recent efforts to soften the effects of the teacher-evaluation law and related legislation would be sufficient to stem the opt-out movement.

"One of the things I've heard is that parents are still mistrustful," said Susan Bergtraum, a former East Williston school board trustee who was among scores of delegates from Long Island.

Bergtraum, who sits on the Nassau BOCES board, also serves as first vice president of the school boards association. She has been nominated to become the state group's next president and is the only candidate named so far. The election is scheduled for Tuesday.

Cuomo's office did not immediately respond to Tisch's remarks. Some leading legislators have left the door open for changes in the evaluation law during their next session, which begins in January.State Sen. John Flanagan (R-East Northport), during an interview last week with National Public Radio on WCNY in Syracuse, said he believes any required changes probably could be made by the Regents and their staff in the Education Department.

"And if need be, which I think is probably unnecessary, you can have legislative intervention," Flanagan said.