Hillary ClintonHillary Rodham ClintonKaine wields Spanish skills in Miami VP appearance Kaine showcases faith and family in VP debut Clinton: Trump's 'I alone can fix it' message is not democracy MORE scored points with the Wisconsin Democratic debate audience by attacking the state's governor, Republican Scott Walker.
Clinton criticized presidential rival Bernie SandersBernie SandersKaine showcases faith and family in VP debut Clinton unveils Kaine: He's everything Trump and Pence aren't Sunday shows preview: Focus shifts to Dem convention MORE's plan for free college tuition as unworkable, saying it depended on Republican governors like Walker.
"Sen. Sanders's plan really rests on making sure that governors like Scott Walker contribute $23 billion on the first day to make college free," Clinton said.
The Milwaukee crowd of Democrats applauded her attack on Walker, who has cut education funding during his governorship.
Democrats and labor groups have been tough critics of Walker, who is known for his hard-line stances against government spending and public sector unions.
Walker, a former Republican 2016 presidential candidate, fired back in real time on Twitter.
"While you took big speaking fees, we froze tuition 4 years in a row to make college affordable. #DemDebate," Walker tweeted, addressing Clinton directly.