Milwaukee, Wisconsin (CNN) Bernie Sanders easily won the Wisconsin Democratic primary Tuesday night, but in his victory speech he didn't thank the man who helped push him over the top: Scott Walker.

Over the last five years, the state's unions have been decimated by a series of laws passed by state Republicans and held up proudly by Walker, the Republican governor and one-time GOP presidential candidate, who has become the face of conservative efforts to take the sting out of the once powerful organizations.

And Sanders, appealing to the liberal base here, reminded them about it every time he could.

"In Wisconsin, probably the easiest way to define a Bernie Sanders presidency and a Sanders administration is to tell you that it would be pretty much the exact opposite of a Scott Walker administration," he said at a Sunday night rally in Madison.

A day later, in Janesville, Sanders told supporters he considered the unions "family," and that, "You've got a governor here who is trying to destroy the trade union movement."

"Well I've got some bad news for him," he continued to rising cheers, "and that is that elected president of the United States, we're going to do everything that we can to rebuild the trade union movement in this country."

Sanders' victory gives him momentum going into the northeastern states later this month. The next major contest, in New York on April 19, figures to be an uphill climb -- but Sanders will not go quietly. In the New York State Nurses Association and the Communication Workers of America, he has an Empire State cavalry awaiting his arrival.

"New York is a big, big labor scene and a lot of workers whose national unions have not endorsed Bernie are likely to come and vote for Bernie," said People for Bernie co-founder Winnie Wong. "If you've been paying attention to any labor organizing over the past year leading up to this moment, you'll see that there has been a lot of rank-and-file organizing in support of Bernie Sanders."

Voters from union households in Wisconsin, where similarly decentralized efforts helped bolster Sanders, made up about a quarter of the vote Tuesday night. According to CNN exit polls, he outpaced Clinton by 8 points among them, with 54% to her 46%.

"What we're trying to do now is bring back the momentum with our union brothers and sisters," said Michael Brown, a bus driver for the Milwaukee County transit system and member of the Sanders-backing Amalgamated Transit Union. "I think we're coming back. We're all one now. We took a big blow, but we're still here."

How Walker kicked union members into action

In the wake of Walker's reforms, organized labor in Wisconsin has splintered. The new governor signed Act 10, which stripped many public sector unions of most of their collective bargaining rights, in 2011, sparking mass protests in Madison and setting the stage for a recall election a year later. But efforts to oust him were rebuffed, twice, first in the spring 2012 vote, then again in 2014.

The breakdown of the state's traditional labor structure -- much of it directed from the national level -- has given local groups more power and, because of laws that generally require workers to opt-in to their unions, attracted more progressive, politically aggressive members.

"Before Act 10 we had 100% membership because you had to join," said Kim Schroeder, president of the Milwaukee Teachers' Education Association. "Of that, maybe 5-10% were active in the union. Now we have 70% of what we could have, but everyone of those 70% has made a choice -- it's a value of theirs to be a part of the union which breeds a much higher activism and engagement rate."

Schroeder is a Clinton supporter. His MTEA offices are dressed with photographs and newspaper clippings from the 2011 labor protests in Madison. He worked his first campaign in 1992, for former President Bill Clinton. When the National Education Association, the nation's largest teachers union, announced in October it was backing Clinton, the MTEA followed suit.

But his members, Schroeder told CNN, were not pleased with the timing of the decision.

"We heard from some who weren't real happy about the endorsement early, any early endorsement," he said, describing his union -- just a day before the vote -- as "split on the issue."

Crisis for labor created an opportunity for the movement's progressives

This is not how organized labor in the state worked before Walker came to power, turned it upside down, and forced its leaders to rethink their means of building and maintaining power. Diminished ranks and the siege mentality that followed have empowered more vocally progressive members, the kind of voters anxious to collect signatures and canvass their neighborhoods -- that is, just the type who are more likely to pull the lever for Sanders.

On Saturday, fewer than 72 hours out from the primary, the senator's supporters gathered in a snowy park in northern Milwaukee. Dozens of people in the Sanders campaign's red, white and blue -- along with a couple holding "Birdie Sanders" signs -- huddled as speakers took turns preaching to the choir.

Among them was Martin Horning, a retired Milwaukee high school teacher but still active member of the MTEA. He told CNN that Walker's Act 10 had pushed him and other colleagues into early retirement.

By voting for Sanders, Horning said, he and his fellow union members were "going to send a message -- we're down but not out."

"In spite of the control of the state government by these right-wing zealots, there is a strong progressive tradition here in Wisconsin," he added, "that has not been defeated by this setback."

Riding the Walker backlash

The renewed focus on bread-and-butter Democratic principles, especially within organized labor, arrived in step with Sanders' message, the University of Wisconsin-Madison's Barry Burden, director of its Elections Research Center, told CNN.

"Sanders has been offering these populist messages about providing a living wage, trying to fight the forced of globalization, keeping jobs in this country, providing universal health care, raising the minimum wage -- those are really resonant issues with union members," he said. "He's hammered those more consistently than anyone else. And I think union members have been attracted to that."

A fever to send a message to Walker was not limited to the union members most deeply affected by the Republican's signature legislation. The local chapter of Michael Brown's Amalgamated Transit Union, which bargains with the federal government, has been mostly unaffected by the new laws.

But the winds of solidarity -- and a familial bond -- led Brown to Madison in 2011, when he protested alongside his sister, a teacher, against Act 10.

"The impact (of the law) was hard on her," he said. "She's still teaching. She's still fighting. But this is not over at all. This battle is just beginning."

Walker, who appeared alongside another Wisconsin winner on Tuesday night, the Republican Ted Cruz, doesn't face another reelection challenge until 2018. Expect to hear more about him -- from both sides of the presidential race -- as the November election nears.