New York is finding itself increasingly isolated in its effort to continue using tests tied to Common Core standards for teacher evaluations.

On Tuesday, a senior executive with the Bill & Melinda Gates Foundation said the organization agrees that test scores shouldn’t be used for “high-stakes decisions on teacher evaluation or student promotion for the next two years”—adding a significant dose of national criticism to the growing scrutiny of New York’s teacher evaluation plans. Though the state isn’t mentioned by name, the message applies directly to New York, which has simultaneously rolled out new Common Core-aligned state tests and a new teacher evaluation system.

For more than a year, Education Commissioner John King has rebuffed calls to lower the stakes for teachers as the state adopted the new, tougher standards. New York’s fast pace stands in contrast to that of other states, including Kentucky, Colorado, Louisiana and Maryland, whose deliberation is specifically praised in the letter by Vicki Phillips, the director of the foundation’s College Ready initiative.

“Each of these states is taking a different approach, but they all are listening to teachers, and they are all taking steps to align their approach with what teachers need to make the standards succeed,” Phillips wrote.

Phillips represents a powerful voice in national education policy debate, and one that typically backs King’s aggressive agenda. Through its research and advocacy, the Gates Foundation has poured millions of dollars into a nationwide effort to encourage states to overhaul their evaluation laws and develop new systems that factor in student test data.

The Gates Foundation isn’t alone in its decision to temporarily back away from using Common Core-aligned tests to rate teachers. Gov. Andrew Cuomo has in recent weeks acknowledged the concerns long raised by teachers tasked with implementing the standards.

Teachers unions say schools haven’t been prepared to teach to the new standards that are reflected in the tests, which require more critical thinking and a deeper understanding of numeric operations. And the state not released Common Core curriculum as often as districts had expected, adding to the challenges.

“Flawed Common Core implementation has severely damaged confidence in the accuracy of evaluations,” Cuomo said last month, according to Newsday. “I believe we must work diligently to remedy that situation with a legislative solution this session.”

Phillips echoed those concerns in her letter.

“No evaluation system will work unless teachers believe it is fair and reliable, and it’s very hard to be fair in a time of transition,” Phillips wrote.

The added pressure makes changes to the state’s teacher evaluation law increasingly likely. But the legislative session ends in a week—and it’s unclear if there is enough political will in the State Senate to tackle teacher evaluations in such a short period of time.

New York has already taken a number of steps to delay the impacts of new standards and tests. For instance, test scores can’t be included on student transcripts or used by schools as primary factors when it comes to admissions or grade promotion decisions.

Teachers argue that they should get the same kind of protection that students get.

“If the tests shouldn’t be used to penalize kids — and they shouldn’t be — it’s only fair to extend that to teacher,” said Karen McGee, president of the New York State United Teachers, which today launched a $200,000 advertising blitz to make that argument to lawmakers.

In response, state education officials have emphasized that state tests still count for less than half of a teacher’s evaluation. And King said that few teachers, if any, will be negatively impacted by evaluations until 2015, more than five years after the state adopted the Common Core standards and passed the teacher evaluation law.

“I think we struck the right balance in the law we developed in 2010,” King said in an interview last month.

Board of Regents Chancellor Merryl Tisch warned that changing the law to reduce the role that testing plays in a teacher’s evaluation could cost the state money. New York received nearly $700 million in federal funding to change its teacher evaluation law in 2010.

“I have not heard anything that indicates to me that the state of New York is willing to walk away from that federal grant,” Tisch said last month.

But there is little evidence that the state would be risking that money if it does opt not to use Common Core tests on evaluations. Last year, Education Secretary Arne Duncan told some states that they could wait until 2016 to evaluate teachers using Common Core-aligned state tests.

The bigger question is how student performance would be factored into teacher evaluations for the next two years if Common Core state tests can’t count. The law currently requires 40 percent of a teacher’s evaluation be based on student learning measures and if state tests can’t count, officials will have to come up with a different measure to take their place.

A spokesman for NYSUT said that piece of legislation was still under discussion.