HARRISBURG — U.S. Sen. Pat Toomey waded into a budget fight in Pennsylvania on Monday over substantially expanding state taxpayer support for private and religious schools that is stoking pushback from public school advocates.

Democratic Gov. Tom Wolf is expected to veto the measure, but Toomey, a Republican, wrote to urge him to sign it and nearly doubling a tax credit program, increasing it by $100 million to $210 million a year.

Approximately 40,000 children are on a waiting list for the taxpayer-funded scholarship aid to help pay their tuition, Toomey wrote.

“The educational futures of Pennsylvania children should not be jeopardized by political games or partisan politics,” Toomey wrote. “I urge you to sign this legislation.”

Under the 18-year-old Educational Improvement Tax Credit program, corporations and businesses can direct tens of millions in tax dollars to private and religious schools. The existing $110 million program subsidizes those donations with a tax credit of up to 90%, meaning a donation of $100,000 may cost the donor $10,000.

Toomey wrote that a few thousand dollars in scholarship money can mean the difference between “being trapped in a failing school or having the opportunity to pursue higher-quality education of their choosing.”

Wolf, who campaigned for office on raising support for public schools, still plans to veto the bill, his office said in statement Monday.

The tax-credit program lacks accountability, transparency and oversight provisions, Wolf’s office said. In addition, Pennsylvania’s public schools remain underfunded while the legislation lacks a source of money to finance “such a substantial and unprecedented funding escalation,” it said.