A few months is not enough time to thoughtfully rework a teacher evaluation system, Chancellor Carmen Fariña said Thursday, joining a growing number of education officials critical of the tight timeline included in a new state law.

The changes require state education officials to hash out most of a new teacher-grading system over the next two months. Only then will districts and their teachers unions be able to negotiate a host of details, like how to introduce observations from outside educators. The law gives districts until Nov. 15 to implement an updated plan or lose an increase in state funding — for New York City, a $400 million prize.

On Wednesday, Board of Regents Chancellor Merryl Tisch she called for a one-year deadline extension for “districts facing hardship,” an unusual proposal that comes less than a month after Gov. Andrew Cuomo and the legislature established the November deadline in budget negotiations. Tisch’s proposed extension, which she first floated last week, came as Cuomo and lawmakers have come under intense criticism for approving the new evaluation framework and its timeline for implementation.

“Over the past few weeks, I’ve heard from administrators, teachers and school boards across the state,” Tisch said in a statement. “They’re concerned about the very tight timeframe, and they’re right.”

Just hours after Tisch floated the extension, which she said she would try to do without changing state law, Assembly Speaker Carl Heastie and Assembly Education Committee Chair Catherine Nolan praised the move at “the right one.”

Cuomo’s office, meanwhile, did not dispute its legality.

It’s now up to the State Education Department to define what would warrant “hardship” for a district to seek the extension. Fariña, speaking to reporters at a pre-kindergarten outreach center on Thursday, said she and Tisch were on the same page and suggested the November timeline might be too soon for New York City.

“I think she’s hearing what I’m hearing,” Fariña said, “that to radically change what we’re doing now and do it so quickly would not do a good job. So I appreciate her statement. I certainly will support her opinion.”

Teachers under the new evaluation system will still be graded on student performance and classroom observations. But the new system will represent the second state-mandated evaluation overhaul in three years for New York City, upheaval that has frustrated teachers.

Fariña will also lose control of many portions of how teachers are evaluated. Under the current system, 80 percent of evaluations are negotiated by local officials and local unions, while the new framework leaves the most important details up to state education officials.

Technically, that means a lot less negotiating work for Fariña and United Federation of Teachers President Michael Mulgrew this summer. But they will still have decisions to make. Whether to add a second measure of student performance (or discontinue use of the city’s much-touted performance assessments) will be decided locally, as will deciding whether teachers can be observed by their peers.

The evaluation law also explicitly states that other measures, such as rating teachers based on student surveys, are prohibited. That means that the city’s two-year pilot program, which this year will include survey results at 50 schools, will likely be shuttered.

Fariña cautioned against making any decisions quickly, and said she expected to continue talking with Tisch and the Board of Regents about the pace of change.

“We can’t keep changing the system year by year because it’s a new fad or a new way of doing things,” Fariña said. “We’ve got to have some stability.”

Since the new evaluation law was passed as part of budget negotiations earlier this month, Fariña has spoken sparingly about the changes, although she was a more outspoken critic of Cuomo’s proposal when it was still being haggled over in March. In her only comments on the evaluation system prior to Thursday, Fariña reiterated concerns about how heavily test scores will factor in evaluations and about allowing teachers to be observed by outside educators.

In two weeks, state officials are holding a day-long event in Albany meant to provide a forum for such concerns. Tisch and her colleagues on the Board of Regents have asked for feedback on the issues that still need to be settled by the education department before the end of June, like defining the role of the outside evaluators.

Representatives from teachers unions, including the city’s United Federation of Teachers, principals unions, education researchers, and other experts have been invited to the May 7 summit, which is not open to the public. Officials are soliciting public comment through an email address, and the event will be viewable online.

“We will be urging the Regents to adopt regulations that limit the impact of the state tests, maximize local control and help teachers grow throughout their careers,” Mulgrew told UFT members in a letter this week.

But state officials are trying to manage expectations about their power to shape the new system, which was laid out in legislation passed at the beginning of April. A presentation from Deputy Commissioner Ken Wagner emphasized that “much of the evaluation system is strictly prescribed by statute.”

The state appears to have the most authority around classroom observations, which will count for about half of a teacher’s evaluation. Observations will have to come from at least two people, a school supervisor and an outside evaluator, but how much weight each of their ratings is worth is up to the department. The Regents are also charged with setting a minimum number and length for the observations and with deciding what rubrics can be used.

Several other issues will be up for discussion at next month’s event, according to a memo Wagner sent to districts this week. That includes the mechanism for converting scores into one of four ratings — ineffective, developing, effective, and highly effective — on both the student performance and observation categories. Previously, that was left up to districts and was seen as the reason more than 60 percent of teachers outside of the city last year received the highest rating possible.

The state has until June 30 to finalize regulations for the new evaluation law. New York City will have until Sept. 1 to negotiate a new plan and submit it to the department for review, although that timeline could change if Tisch’s proposed extension goes unchallenged.

The most daunting task for the city will be to prepare what could amount to thousands of new independent observers in just a few months, said Evan Stone, executive director of the teacher advocacy group Educators 4 Excellence.

“That’s going to be very difficult to implement,” Stone said. “It’s a large number of people to train and get up to speed.”