As Wisconsin voters head to the polls, Hillary Clinton hit the state's governor in an ad attacking Bernie Sanders' education plan. "Scott Walker slashed UW's budget by $250 million which could crush students and families across Wisconsin. Now maybe you've heard of Bernie Sanders' free college plan," the Clinton ad posted to Twitter says. "But believe it or not under the Bernie Sanders plan Scott Walker would decide whether or not you get free college."

The ad attacks Walker, possibly hoping to mobilize some of the Democratic voters who tried to recall him. It also tells Democrats that Sanders' education plan will require the cooperation of Republican governors.

"We shouldn't let Scott Walker get in the way of an affordable education in Wisconsin," the ad concludes.

Going in to Tuesday's primary the former secretary of state trails Sanders by less than 3 percentage points in the RealClearPolitics polling average for Wisconsin.