The Education Coalition, groups comprised of teachers, administrators and parents, say public schools have endured $18 billion in cuts over three years.
Districts have shortened their academic year, cut nonessential classes and let 30,000 teachers go.
They warn that an additional $2 billion will be lopped off if Californians don't agree to extend the temporary tax hikes another five years.
"The notion of another couple of billion on top of everything is frightening to us and should be to anybody who cares about the quality of education in California," said Bob Wells of the Association of California School Administrators.
Republicans will block attempts to get the tax vote on a June ballot, even if it means more cuts to schools could be prevented.
Many believe more cuts are possible without affecting the classroom by simply changing laws that protect union jobs.
"Why don't we let volunteers come in and run libraries? We have state codes that say we can't do that at all," said state Sen. Bob Huff (R-Diamond Bar).
Even if the tax extensions make it to the ballot, there's no guarantee voters will approve them, considering they already turned down extending the taxes in 2009.
That's a prospect upsetting to parents like Amber Miller.
"I think we all have those kinds of worries," Miller said. "If it hadn't passed before, it's a possibility it won't pass again."
The California Teachers Association says it's ready to help finance a campaign to get those temporary tax hikes extended. Early polling shows if tax hikes are connected to education, voters tend to support them.