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Hillary Clinton is ratcheting up her attacks on Bernie Sanders

She says her Democratic primary rival is a "pie in the sky" politician

Green Bay, Wisconsin CNN  — 

Hillary Clinton has used the last two days of campaigning in Wisconsin to cast her Democratic presidential rival Bernie Sanders as a “pie in the sky” politician making promises he can’t keep.

The tactic is one Clinton has revisited time and time again on the campaign trail, but speaks to the fact that Clinton and her campaign are well aware Sanders is likely to do well in the historically liberal state.

The former secretary of state told voters in Madison on Monday that she wasn’t a candidate just proposing “pie in the sky stuff” in order to convince people to vote for her.

On Tuesday in Green Bay, Clinton suggested that some politicians that talk about taking on special interests – something Sanders often does – are all talk, no action.

“I love it when people talk about taking on special interests and fighting special interests and fighting the powerful,” Clinton said. “I mean, those are great speeches. I have done it.”

Clinton has her work cut out for her in Wisconsin, where Sanders regularly draws large crowds, including almost 10,000 people last year in Madison. She spent the last two days in the state holding five events and visiting a number of local businesses.

“We are working really hard and having a good time doing it,” Clinton said while shopping at Anthology, a small store in Madison on Monday.

Joel Benenson, Clinton’s top strategist, told reporters that the race in Wisconsin would be “close.”

Behind the scenes, aides are acknowledging that it is very possible that Sanders will come out the winner on Tuesday night.

In an effort to pre-but another possible Sanders win, Benenson said Monday that even if the Vermont senator does come out ahead, his win will be narrow and will likely to not make a huge shift in the delegates count.

Despite Sanders wins in Hawaii, Alaska and Washington State, Clinton’s campaign has looked to hang their hat on the more than 250-delegate lead they have run up against Sanders. Aides have said that their lead is “almost insurmountable,” and feel that after April 26 – when states like Pennsylvania, Connecticut and Maryland vote – Sanders will be unable to close their lead.

Clinton’s main policy argument Sanders in Wisconsin has been to knock his tuition free college plan as unachievable given the fact it will rely on Republican governors – many of whom have cut education spending – to put in state money for fund the plan.

“His plan depends on governors like your governor, putting in a lot of money,” Clinton said for a chorus of boos about Wisconsin Gov. Scott Walker. “Now, I’ve got to tell you, having followed from afar the wrecking ball Scott Walker has used against higher education, I don’t think it is all the realistic to say you will get free college as long as Scott Walker chips in about $300 million.”

By taking on Sanders’ college plan, Clinton is going after an issue that is popular among Democrats and Sanders’ core supporters.

Sanders responded to Clinton’s attack during an interview with CNN on Tuesday, acknowledging that Wisconsin will suffer if states with Republican governors decline to fund his plan.

“Well you know what happens to the state of Wisconsin if he does that? California will, Vermont will, states all over this country will. And young bright people will be leaving Wisconsin,” he told CNN’s Erin Burnett. “And I think the people of Wisconsin will tell Scott Walker, this will be a disaster for the future of our state, because when kids leave, sometimes they don’t come back.”