In a letter today to U.S. Secretary of Education Arne Duncan, eight civil rights groups are urging him to reject the petition by nine California districts that want their own tailor-made No Child Left Behind waiver.

The “CORE” waiver request, submitted after California was unsuccessful in getting a statewide waiver, is undergoing a peer review at the federal level. U.S. Department of Education officials have said they want to let these California districts (who go by California Office to Reform Education) know by later this spring whether their request has been granted.

Duncan’s decision on this waiver is being closely watched because it would mean unprecedented flexibility in school accountability for individual districts since waivers thus far have only been available to states. It would also disrupt the traditional role of the states as accountability creators and enforcers. But Duncan welcomed the waiver request as a chance to help districts that collectively educate 1 million students, as the request includes Los Angeles, Sacramento, and San Francisco.

In their letter, signed by the Education Trust, Democrats for Education Reform, the National Center for Learning Disabilities and others, the groups warn that a district waiver would create different sets of expectations across California. They argue that “different expectations far too often means lowered expectations.” And, they warn that granting this waiver could open the door to other requests, even in states that already have state-level flexibility.

“Although the Secretary of Education has signaled that districts in states with statewide waivers will not be eligible for separate waivers, we are concerned this lays the groundwork for a possible future loophole allowing any district to come forward to seek an independent waiver,” the statement says.

During a media round table with several reporters today to talk mainly about President Barack Obama’s preschool push, Duncan said that so far no other districts have applied for waivers. And, interestingly, he said California might apply again. (Don’t forget, California’s first try at a waiver request was so far off the mark that federal officials rejected it outright and didn’t even send it out for peer review.)