Wisconsin Gov. Scott Walker resoundingly beat a recall challenge Tuesday, defeating Milwaukee Mayor Tom Barrett 53 to 47 percent.

The closely watched race was a stunning defeat for organized labor and an indication of the power of unrestrained money following the U.S. Supreme Court’s Citizens United decision.

Walker had come under fire for his attacks on organized labor and collective bargaining. Shortly after being elected, he and the Republican-controlled legislature passed a series of laws that stripped labor unions of their right to collectively bargain and forced them to pay more for benefits. His actions caused walkouts by Democratic legislators and massive protests in the state capital.

Union members from Wisconsin and around the country mounted a massive recall effort, collecting more than 1 million signatures from Wisconsin residents. At the same time, Walker began a nationwide campaign to raise funds to fend off the recall effort.

Walker was able to raise millions of dollars from conservative donors, including the infamous billionaire conservative businessmen the Koch brothers. Because of a loophole in Wisconsin state law, Walker was able to raise unlimited amounts of cash between the time the recall was called for by his opponents and the time the recall actually started. More than $45 million was spent on behalf of Walker, compared to only a little less than $18 million for Barrett at the end of last month, according to the Wisconsin Democracy Campaign, a nonpartisan group that tracks election spending.

But despite this financial advantage, union leaders and progressive activists remained hopeful that Barrett could beat the odds and pull out a win. Former President Bill Clinton came to the state late last week to help rally the cause. Although President Barack Obama kept his distance, he sent a message of support through social media that was broadly picked up by the mainstream media.

Turnout in the special election was extraordinarily heavy, with more than 2 million people casting votes–larger than the 2010 election that brought Walker into office but less than the 3 million who cast ballots in the presidential election that saw Obama get elected.

The implications for the general election remain unclear. Exit polls showed that 51 percent continued to support Obama compared to 44 percent, according to the Washington Post. Wisconsin has gone to the Democrats in presidential elections stretching back to 1988.