And he says the state's public schools "can't take much more underfunding."
Croken also says not all students will be able to take advantage of school vouchers. That's because a private school may not be located near their homes, and some families can't afford to spend extra on transportation.
In addition, the Democrat says the choice doesn't belong to parents as much as school administrators. Public schools are required to enroll all students who live in a district. But private schools can reject students for a variety of reasons.
Iowa Representative Gary Mohr, a Republican from Bettendorf, crossed party lines with eight others to vote against the bill. But other local GOP legislators voted for it.