Parents who participate in the program receive 90 percent of what the state would spend on a student's public school education in a special account. The funds can be used for a child's education at private schools, including those run by churches, for online education, private tutoring or future educational expenses.

About 3,300 Arizona students have been enrolled with an ESA account during the 2016-2017 school year. The greatest participation is in the Tucson Unified District with 305 ESA students.

The expansion law caps the number of new enrollees each year to a half percent of the total number of students enrolled in public school districts and charter schools.

Arizona's Catholic bishops have advocated for school choice measures for decades. Many Catholic school students have long relied on state tuition tax credits, said Ron Johnson, executive director of the Arizona Catholic Conference.

He said the number of Catholic school students utilizing the scholarship accounts is lower because the program is new and had been available to only certain students.

The Phoenix and Tucson dioceses currently have 562 students with the accounts in Catholic schools, Johnson said.

Critics of expanding the scholarship account program said it will hurt public schools by siphoning more funds from them. They said it will only benefit the wealthy, who could secure state tax dollars to pay for private schools their children are already attending.

Opponents also pointed to a 2016 state audit of the program that identified misspending by the scholarship program -- more than $102,000 was misused between August 2015 and January 2016.

The Arizona Catholic Conference is the public policy arm of the bishops of the state's dioceses of Phoenix, Tucson and Gallup, New Mexico, and the Byzantine Catholic Eparchy of Phoenix. Parishes in northeastern Arizona are part of the Diocese of Gallup.