MADISON, Wis. — Outside spending in Wisconsin's race for state superintendent has topped $1 million, the most ever spent by special interests trying to influence the officially nonpartisan race, the Wisconsin Democracy Campaign said Monday.

The group tracks spending on political campaigns, including the one to be decided Tuesday. The race for Department of Public Instruction secretary pits Pecatonica school district superintendent Jill Underly against former Brown Deer superintendent Deb Kerr.

Underly has the backing of the state teachers' union and a wide array of Democrats, while Kerry is favored by many conservatives, including former Gov. Scott Walker.

To date, $797,600 has been spent by groups supporting Underly or opposing Kerr. The American Federation for Children, a group that supports private school vouchers which Kerr also favors, has spent $209,000 to help her in the race, according to the Democracy Campaign.

The biggest spender helping Underly was the liberal group A Better Wisconsin Together, which has put $778,000 into the race. Planned Parenthood Advocates of Wisconsin spent $16,295 and the state teachers union, Wisconsin Education Association Council, spent just over $110 on post cards for Underly.

The previous record high for spending by outside groups in this race was nearly $694,000 in 2009, the year that now-Gov. Tony Evers was first elected state superintendent.