Merryl Tisch, who has served as New York’s top education official since 2009 and come to represent the changes of the Race to the Top era, will step down from the Board of Regents next year, she announced Monday.

Tisch’s term ends in March 2016. When she steps down, it will represent the end of a turbulent period in New York education policy during which the state adopted the Common Core learning standards and overhauled teacher evaluations to account for student test scores, sparking an anti-testing backlash but also coinciding with rising graduation rates.

“I say we disrupted stagnation,” Tisch said Monday of her tenure. “We disrupted complacency and we tried to imbue the system with urgency. I say we took critical steps to reignite and reinvigorate change.”

Tisch has served on the Board of Regents, the state’s 17-member education policymaking body, since 1996. She took control of the board six years ago, and along with education commissioner John King oversaw the implementation of a host of programs spurred by the $700 million federal Race to the Top grant New York won in 2010.

That funding — and Tisch’s influence — transformed the role of the Board of Regents and its chancellor. Once a job that drew little attention, Tisch turned the chancellorship into the face of public education policy in New York.

But in the last two years, Tisch has lost allies and her policies have lost momentum.

King departed for the federal education department at the end of last year. Sheldon Silver, who controlled the Regents selection process, was another important ally, but stepped down as Assembly Speaker earlier this year after being indicted on corruption charges.

A number of Regents supportive of Tisch have left and been replaced with more skeptical appointees. That has lead to some awkward moments this year, with Regents speaking out during meetings in opposition to policies that she shepherded through.

At the same time, Gov. Andrew Cuomo has tried to wrest more control of education policy, pursuing a series of changes to teacher tenure rules, evaluation methods, and the state’s role in overseeing struggling schools last year. The final dollars from the Race to the Top grants are being disbursed this year, leaving state policymakers without key levers to prompt districts to make changes. And the Obama administration this weekend acknowledged that the push for testing in schools had gone too far.

Tisch said she’d made up her mind nearly a year ago to leave at the end of her term and had discussed her decision with several board members. Still, some board members said they did not know what was coming on Monday morning.

“I’m stunned,” said Regent Kathleen Cashin. “I’m in a state of shock.”

Although her tenure will likely be seen favorably by those who wanted New York to make dramatic changes to education policy, she was critical of some change efforts. She was a public critic of former Mayor Michael Bloomberg’s school closure strategy, which she believed resulted in some large high schools “warehousing” groups of the neediest students. This summer, she said she would understand if parents opted out of state tests if their child had a severe disability.

As she made her announcement, though, she pushed her fellow Regents to stay the course, offering a forceful defense of the state’s push to raise standards and improve its assessments and teacher evaluations.

“We cannot back away from standards,” she said. “We cannot back away from assessments that give us an accurate measure of student performance and that informs instruction and curriculum. We cannot back away from the idea that a system like the one that we had for generations where the only way to evaluate a teacher was to rate them satisfactory or unsatisfactory and where almost everyone was always satisfactory can be tolerated as best practice.”

“It’s not good for teachers,” she added. “It’s not good for principals. It’s not good for students and it’s not good for communities.”

The immediate reactions to Tisch’s announcement reflected her polarizing status among New York’s sharply divided education groups, who tend to view Tisch either as a champion of sorely needed reforms or an apologist for misguided and poorly executed overhauls.

Jenny Sedlis, executive director of StudentsFirstNY, an advocacy group that backed the state’s move toward tougher learning standards and teacher evaluations, said in a statement that she was “deeply disappointed” that Tisch would not seek reelection, adding that she had served with “integrity and independence.”

But Leonie Haimson, executive director of Class Size Matters and a longtime critic of Tisch’s policies, wrote on Twitter: “Terrific news.”

During the last months of her tenure, Tisch said she hopes to “calm the waters” and around some of the most contentious education issues, including standards and testing. After she steps down, she says she plans to remain a presence in state education policy.

“I plan to continue to be an independent and — you all know — outspoken voice in all of these debates,” she said.