Democratic presidential candidate Hillary Clinton said she has a more realistic college affordability plan than does her rival Bernie Sanders at a campaign rally in Milwaukee on Monday night.

Sanders, a U.S. senator from Vermont, is proposing free tuition for students attending state colleges and universities. But former Secretary of State Clinton said the wealthy should pay for college themselves. She also criticizes Sanders for expecting states to put in some of the funds.

"The way we figure it, under Sen. Sanders' plan, the state of Wisconsin would have to put in $300 million over 10 years for free college, And you have a governor who just cut $250 million from the state higher education budget," Clinton said.

Sanders said his free tuition plan would lead to fewer students dropping out.

Sign up for daily news! Stay informed with WPR's email newsletter.

Clinton is also again taking on Gov. Scott Walker over the issue of collective bargaining for labor unions. Clinton told hundreds of people in Milwaukee that Walker's opposition to some labor groups has hurt the middle class.

"And I look at what your governor has done destroying unions, making it more difficult for families," Clinton said.

Walker said curtailing collective bargaining powers for many public sector unions helps save taxpayers money and said signing right-to-work legislation that affected union organizing brought Wisconsin in line with many other states.

Both Sanders and Clinton will campaign in Wisconsin on Tuesday, as will the three Republican presidential candidates.