Florida is suddenly in danger of stumbling in its quest for a share of $4.5 billion in federal education money aimed at school reform.

Teachers union officials on Thursday called the state's bid "fatally flawed" and said there isn't a local union that can support it.

That could mean trouble for Florida, which stands to lose up to $700 million in federal Race to the Top funds to improve teacher evaluations, tie teacher pay to student performance and turn around struggling schools. Union partnerships are a requirement, as many of the reforms need contract negotiations.

Florida education commissioner Eric J. Smith expressed regret over the unions' stance, and the conservative Foundation for Florida's Future said it showed they were "willing to play union politics at the expense of teachers and students."

But even the reform-minded Hillsborough County teachers union says it couldn't support Florida's plan as written. That union supported a $100 million grant from the Bill & Melinda Gates Foundation to the Hillsborough school district that will do many of the same things, though over a seven-year period.

"They're holding Hillsborough up as a model for this particular application," said union president Jean Clements. "But if I'm reading this document correctly, I could not sign it as it reads right now."

Experts have hailed the federal Race to the Top effort as a game-changing plan to transform public education. Rather than imposing changes, it offers stimulus money to states and districts that support what U.S. Secretary of Education Arne Duncan has described as proven reforms.