PHOENIX — Opponents of Arizona’s new universal private school voucher program on Tuesday succeeded in blocking the law until voters can weigh in next year, barring a successful court challenge or an outright repeal of the new law by the Legislature.

County recorders reviewing a random 5 percent sample of the 111,000 signatures certified by the Arizona secretary of state have now verified enough valid signatures were gathered to send the measure to the ballot.

Maricopa County results put the effort over the top with a verification rate of 86.6 percent, a high percentage for such efforts. Ten other counties also have finished their reviews, and all but three certified more than 80 percent of the signatures belonged to registered voters.

State officials said about 70 percent of the signatures needed to be valid to meet the minimum threshold.

Voucher backers have already filed a lawsuit seeking to invalidate the voter referendum. Republican lawmakers and Gov. Doug Ducey enacted the voucher proposal this spring, with backing from the American Federation for Children, the school-choice group formerly led by current U.S. Education Secretary Betsy DeVos.

Under Arizona law, new laws can be blocked by a signature-gathering effort. Voucher opponents put together a grassroots effort to gather the signatures in the allotted 90 days after the Legislature adjourned in May.

The last time a referendum blocked a law, the Legislature repealed it. That case involved a sweeping 2013 election law overhaul that included trimming the state’s permanent early voting list and a host of other provisions that incensed voter-rights advocates of both major parties.

Republican House Speaker J.D. Mesnard said in an interview last week that repeal of the voucher effort would be an option.

“I think it’s too early to say what we would do,” Mesnard said. “We’ll obviously let it play out over the next weeks in the court system and let all the various challenges go through and then figure out what the best approach is.”

A major concern for Mesnard is the Voter Protection Act, a voter-approved law that prevents the Legislature from making substantive changes to laws enacted at the ballot.

Dawn Penich-Thacker, spokeswoman for the group that collected the signatures, Save Our Schools Arizona, said the high signature validity rates show voucher backers are going against the will of the people if they continue their legal challenges to the referendum.

“People want a chance to vote on this, and I think it says a lot that they’re willing to throw this many resources toward simply keeping people away from the ballot,” she said. “If they’re confident that this is what Arizona wants, you would think they would throw these resources into educating us about why it’s such a great deal.”

The legal challenge points to what voucher backers say is a fatal flaw in the introduction to the petition sheet, noting that it gave this year’s legislative session an improper legal description. The lawsuit also seeks to invalidate petition sheets for various flaws, including inaccurate or missing disclosures about the circulator’s paid or volunteer status.

A spokeswoman for the American Federation for Children, Kim Martinez, said Tuesday the group believes the measure doesn’t qualify for the ballot based on the lawsuit’s contentions.

A court date hasn’t been set to hear the lawsuit.

If the lawsuit doesn’t succeed and the Legislature doesn’t repeal the law, it will be on the November 2018 ballot.

Arizona first passed a voucher program, technically called Empowerment Scholarship Accounts, for disabled students in 2011. The program differs from traditional vouchers by giving state funding directly to parents, who can use the cash to pay for private school tuition, home-schooling or other education expenses.

The program has been repeatedly expanded, and it now covers a third of all students. Despite those changes, only about 3,500 students now use it, and more than half are disabled.