The state Supreme Court on Tuesday derailed Louisiana’s expanded voucher program, setting off a scramble in the Legislature on whether and how to fund the effort.

The ruling, a setback for Gov. Bobby Jindal, upheld and expanded on a decision last year by 19th Judicial District Court Judge Timothy Kelley, of Baton Rouge.

It sets up a late session battle on how to finance the aid, which triggered weeks of pointed arguments in the Legislature last year.

Voucher opponents, who have blasted the funding plan for months, were gleeful after hearing news of the ruling.

“We are not surprised, but we are pleased,” said Steve Monaghan, president of the Louisiana Federation of Teachers and one of the plaintiffs in the lawsuit that sparked the ruling.

Jindal and his allies noted that the court did not toss out vouchers entirely, just the funding mechanism.

The governor told reporters he is confident a new funding method will be approved, and that parents of voucher students “can breathe a deep sigh of relief.

“We’ll work with the Legislature to appropriate that money,” he said during a news conference at the State Capitol. “So it’s a fairly simple fix.”

The ruling, which is not expected to affect day-to-day routines for students with vouchers now, still set off shock waves among some parents.

“I panicked when I first heard the ruling,” said LaQuinta Valentine, whose son Tyrell Jackson is a sixth-grader at Hosanna Christian Academy in Baton Rouge.

Valentine, like other parents, said her chief worry is whether her child can remain in the program for the 2013-14 school year.

“I’m very concerned.” Valentine said.

Michael Faulk, president of the Louisiana Association of School Superintendents, said the decision will likely force the state Board of Elementary and Secondary Education to come up with a new proposal to fund public schools for the 2013-14 school year.

The one approved earlier this year, which is awaiting legislative action, includes the use of public school dollars to fund vouchers.

Faulk also said that, if voucher backers want to continue the aid, they will have to come up with $30 million to $50 million outside of the funding mechanism for public schools.

Vouchers are state aid that allow some students who attended public schools rated C, D or F to attend private and parochial schools at state expense.

Nearly 5,000 students are using vouchers in the current school year, and nearly 8,000 students are scheduled to do so for the next school year.

The key issue before the court was whether the source of public school aid — it is called the Minimum Foundation Program — could be used to pay for vouchers, which finance tuition and some mandatory fees.

The 6-1 ruling struck down the MFP funding mechanism that the Louisiana Legislature overwhelmingly approved last year.

State Superintendent of Education John White said earlier that the voucher aid alone costs about $22 million per year.

The state is facing a $1.3 billion shortfall for the upcoming financial year to maintain aid for state services at current levels.

Jindal said vouchers can be financed with general revenue dollars, much like they were paid for when the aid was limited to New Orleans before last year’s statewide expansion.

Monaghan said he was also gratified that the court ruled that last year’s school aid authorization bill — it was Senate Concurrent Resolution 99 — failed to gather the needed votes for final approval, another Louisiana Federation of Teachers argument.

Brian Blackwell, an attorney for the Louisiana Association of Educators, said the state needs to collect the roughly $26 million in taxpayer dollars spent so far on vouchers in private and parochial schools.

“These are private entities that own and hold the state’s money,” Blackwell said during an afternoon news conference on the steps of the State Capitol.

Eric Lewis, who is state director of the Louisiana branch of the Black Alliance for Educational Options, which is a major backer of vouchers, said he is confident the assistance will continue.

“Superintendent White has committed that the program is going to be funded,” Lewis said, a view echoed by other Jindal allies.

Josh LeSage, administrator for Hosanna Christian Academy, which has the third-largest number of voucher students in Louisiana, said he is optimistic funding for the program will continue. “I am confident,” LeSage said.

He said 277 of the school’s 600 or so students qualified for vouchers in the current school year.

Critics of the law have argued that MFP dollars are reserved solely for public schools and challenged last year’s law on that basis.

The court agreed.

The ruling said: “We agree with the district court that once funds are dedicated to the state’s Minimum Foundation Program for public education, the constitution prohibits those funds from being expended on the tuition costs of nonpublic schools and nonpublic entities.”

Backers said the aid offers students a way out of troubled public schools.

The ruling comes at the midway point of the Legislature’s two-month gathering.

It also re-opens a volatile topic in the final four weeks of the session.

Any bid by Jindal and his allies — they pushed last year’s voucher law expansion — will spark heated arguments.

The ruling also applies to public school classes offered by private providers, which is called course choice, that were also set to be financed with the assistance of MFP dollars.

The 2013 regular legislative session ends on June 6.

Scott Richard, executive director of the Louisiana School Boards Association, another plaintiff in the lawsuit, also praised the ruling.

“We would have hoped it would not come to this point,” Richard said.

Koran Addo and Mark Ballard of The Advocate’s Capitol news bureau contributed to this report.