Parents like private school vouchers so much that demand is exceeding budgets in some states

In some states, higher-income families can now use taxpayer money to cover private school tuition -- and more people than projected are taking the offer, which might force scrambles to shore up state budgets.

It's especially an issue in states like Arizona and Iowa, where at least some families whose children were already in private school can now take advantage of public funding.

“It busts the budget because it’s taking on as a public expense what’s previously been a private cost,” said Josh Cowen, an education policy professor at Michigan State University.

Advocates for school choice pitch vouchers as a way to give students in low-performing schools a way out – and, increasingly, to give parents control over what their children are taught.