State superintendent Tony Evers and challenger Don Pridemore are clashing over expanding the voucher program and freezing public school spending.
The two debated Wednesday before about 300 school board members and administrators at a meeting of the Wisconsin Association of School Boards.
Pridemore is a Republican state representative running to oust Evers as head of the Wisconsin Department of Public Instruction. Evers is completing his first term in that office.
Pridemore supports Gov. Scott Walker's proposal to expand vouchers and freeze public school spending. He said budgets are tight and schools shouldn't expect to be able to spend more.
Evers opposes the governor's plan and wants spending to go up $225 per student.
The debate comes less than three weeks before the April 2 election.