Lawmakers have approved a bill that would nearly double a tax break for people and businesses who contribute to private school scholarships and similar public school alternatives.

They did so with almost no support from Democrats.

And now, Democratic Governor Tom Wolf is saying he doesn’t understand why the expansion is necessary.

Republicans argue the Educational Improvement Tax Credit helps low-income students who are stuck in bad public schools. Many Democrats say it unfairly routes money away from those struggling schools.

The EITC program has grown incrementally and substantially since it started in 2001—often with bipartisan support.

But even the Democrats who generally favor the credit say this particular increase is too high.

Along with almost doubling it, the bill—sponsored by GOP House Speaker Mike Turzai—adds an automatic 10 percent escalation every year, as long as the credit stays popular. And it raises the income cap for eligible families from $85,000 to $95,000.

The measure breezed through the GOP-controlled House and Senate, and is expected to be part of ongoing budget negotiations.

Governor Tom Wolf declined to share his specific plan for the bill, saying only that he’s “going to look at it.”

But his initial comments on the proposal weren’t positive.

“I don’t understand—that’s a 40 percent increase in an expenditure, and I haven’t heard any suggestion about how it’s going to be paid for,” he said. “There’s something missing here.”