WASHINGTON — Senate education leaders yesterday unveiled a hurricane-relief package intended to prevent a bitter fight over vouchers. Instead, it seemed to start one.

The largest teachers’ union and civil rights groups condemned the plan as a national experiment in private-school vouchers, which bill sponsors called a mischaracterization.

Notably, the interest groups found themselves at odds with a lawmaker they often count on for support — Sen. Edward Kennedy of Massachusetts, the education committee’s top Democrat.

“We are not supporting that — and that’s a big not. It’s a voucher bill,” said Reg Weaver, president of the National Education Association.

Kennedy and fellow Democratic Sen. Christopher Dodd of Connecticut developed the bill with education committee Chairman Mike Enzi, R-Wyo., and Sen. Lamar Alexander, R-Tenn. The sponsors hoped to move it through the Senate quickly, possibly by today.

It would allow both public and private schools to seek reimbursement of up to $6,000 for each displaced student they serve, or $7,500 for each student with disabilities. Total cost: $2.4 billion. Hurricane Katrina forced more than 370,000 students to flee the Gulf Coast.

Under the plan, the federal money would flow through public school districts, which would then be charged with making payments to the eligible private schools. The bill would ban public money from being spent for “religious instruction, proselytization or worship.”

Kennedy has criticized a White House plan to create vouchers for Hurricane Katrina victims. By contrast, he said his bill provides immediate relief to public and private schools that have helped in a time of crisis, and “without opening political or ideological battles.”

That didn’t sway the Rev. Barry Lynn, executive director of Americans United for the Separation of Church and State.

“I don’t see the difference between this program and a voucher program,” he said. “This gives millions of dollars in virtually unrestricted cash grants to religious schools.”

Critics said they favored a different model, already established under law, in which school districts purchase services from private schools but retain oversight over the money.

Kennedy spokeswoman Laura Capps said the senator used that idea as a starting point but opted for a plan that allows money to get to the affected schools more quickly. Participating schools would be banned from discriminating based on religion, race or gender, she said.

“We are pleased that senators from both parties understand the hurricane did not discriminate between public and private schools, and neither should our public leaders,” said Scott Jensen, director of national projects for the Alliance for School Choice.

But the bill’s civil rights protections may not be enforceable in the private schools if they get their federal money indirectly, said Tanya Clay, senior deputy director of public policy for the liberal People for The American Way. “It’s murky,” she said.

The program would last for one year only. Terri Schroeder, senior lobbyist for the American Civil Liberties Union, said it would set a precedent: “What about the next crisis? What you’re saying is that it is now acceptable to divert massive amounts of public funding.”

In the House, Republican education leaders this week introduced legislation that would create accounts for parents of children affected by the hurricane, worth up to $6,700 per student. Students could use the money to attend a public or private school for one year.