The blowback from Wisconsin governor Scott Walker’s union-busting crusade has only just begun—and it may soon hit the governor where it really hurts: in the deep pockets of his biggest donors. Workers have begun organizing a “Move Your Money Campaign” against M&I Bank, whose employees are among his chief financial backers.

 M&I Bank is the largest bank in Wisconsin, and was the recipient of $1.7 billion in TARP bailout money from the federal government. The bundled contributions from M&I executives were Walker’s second-largest source of campaign funds. According to records provided by the Sunlight Foundation, executives at M&I Bank gave $46,308 to Walker’s campaign. And now, a group of local unions in Wisconsin have threatened to pull their money from M&I Bank unless it denounces Scott Walker’s attack on workers’ rights.

“Walker and his henchmen in the GOP have chosen to ignore the people of Wisconsin, but we all know now that they will listen to their big money donors,” says factory worker David Goodspeed, a member of Sheet Metal Workers Local Union 565. “This is an opportunity for donors like M&I to be good corporate citizens and do what’s right for the citizens who bailed them out.”

On Thursday morning, several hundred protesters surrounded an M&I Bank across the street from the Wisconsin State Capitol shouting “You Got Bailed Out, We Got Sold Out.”  International Association of Fire Fighters Local 311 President Joe Conway Jr. told me two union members marched in and pulled a combined $192,000 dollars out of the bank. “Hopefully this sends a message to the bank,” says Conway. “We wanted to illustrate how serious our threat is by having just two of our members pull their money out. “ The union said it plans to escalate actions and will soon begin handing out flyers at protests asking people to move their money.

A senior union researcher estimates that unions have at least $1 billion invested in M&I Bank, mostly through pension funds. Discussions are going on at the highest levels of the labor movement about how exactly to leverage this financial clout in the political debate in Wisconsin. Since the Bank of Montreal is in process of purchasing M&I Bank, US unions have reached out to the Canadian Labour Congress to urge their involvement in a disinvestment campaign.

“It’s good to remind these corporations that there are risks as well as profits involved in supporting right-wing political campaigns,” says Mark Weisbrot, co-director of the Center for Economic and Policy Research. “Unions must use their economic power to fight for labor rights.”

With over $6 trillion of workers’ money in retirement plans, pension funds, profit-sharing and stock plans and union reserve funds, workers have the ability to reshape the economy and political priorities of the economic elite.

Unions have had some success with this tactic in the past. In 2009, a coalition composed of organized labor, religious groups, community organizations and MoveOn.org spearheaded a successful campaign to get Ken Lewis pushed out as chairman of Bank of America.

With few tools in their arsenal to stop the escalating attacks, unions may increasingly turn to this tactic of moving their money to protect their rights. While workers may be on the defensive, fending off right-wing assaults like Walker’s, they are also realizing the power they have in society and the economy.