Republican Arizona Gov. Doug Ducey has signed a major school voucher expansion bill that will extend eligibility to all 1.1 million state schoolchildren despite vehement opposition from Democrats who believe it will undercut public education and cost taxpayers untold millions of dollars.

"When parents have more choices, kids win," Ducey tweeted after the House and Senate barely passed the legislation Thursday evening.

Republican backers call the measure a needed school choice expansion, but opponents argued it will benefit the wealthy, who they say will use state money to pay for private education they would fund anyway.

The governor wrote: "Arizona has been the nation's leader in educational & parental choice for two decades. Let's keep it going, & help all Arizona kids succeed!"

The program will give Arizona one of broadest voucher programs in the nation.

The law comes at a time with considerable national momentum behind school choice, punctuated by the confirmation of Betsy DeVos as President Donald Trump's Education Secretary. The billionaire is a vocal supporter of school choice and voucher programs, putting the nation's top education official firmly behind the Arizona proposal.

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DeVos tweeted Thursday night lauding the decision, calling it a "big win for students and parents in Arizona."

Technically called Empowerment Scholarship Accounts, the Arizona program allows parents to take between 90 percent and 100 percent of the state money a local public school would receive to pay for private or religious education. The average student who isn't disabled will get about $4,400 a year, but some get much more.

Nevada has a similar plan applying to all students, but its funding mechanism was recently struck down by the state Supreme Court.

The original Arizona plan was estimated to cost the state general fund at least $24 million, but the revised plan adds up to a savings of $3.4 million by 2022.

Democrats questioned findings by the Legislature's budget analysts, noting that the analysis also said children of wealthy parents who already planned to send their children to private schools would now get state money to help pay for that tuition.

The measure had been stalled for nearly two months as opposition from a handful of GOP lawmakers and all Democrats left the measure short of votes.

Minority Democrats said the expansion will swamp the state's general fund and siphon cash from public schools, which already rank near the bottom in terms of state funding nationally. They predicted the enrollment cap will be gone.

"The cap will come off," House minority leader Rebecca Rios said. "Make no mistake."

Since the initial program was adopted in 2011, it has expanded to cover about a third of all students, including children attending failing schools, those living on Indian reservations, foster children and children of military members.

Despite those increases, the program has remained relatively small, but expanding it to all students would allow parents who now send their children to private schools to use the program.

Ducey said at a January school choice event that he'll continue to be an advocate for using state tax money for charter and private schools and home-schooling. That's despite low funding for public schools in the state.

Ducey proposed a 2 percent raise for teachers over five years in his budget, a figure that has been widely panned by education advocates.

"I was really surprised to hear that the governor was making this a priority," said Joe Thomas, president of the Arizona Education Association, which represents public school teachers. "I don't remember this as part of state of the state address. He called for teacher raises."