Kloppenburg, a little-known state attorney, began the race as a heavy underdog. Prosser entered the campaign with 12 years' experience on the court and is well-known in conservative circles after a stint as Republican Assembly speaker in the 1990s.

But Kloppenburg's supporters seized on the anger created by Walker's efforts to erase nearly all public workers' union rights in Wisconsin. They linked Prosser to Walker and transformed the race into a referendum on the governor, and her campaign surged into the April 5 election.

At first it appeared Kloppenburg had pulled off the upset. Initial results showed she had defeated Prosser by about 200 votes, and she declared herself the winner the day after the election.

The next day, Waukesha County Clerk Kathy Nickolaus announced she had failed to report 14,000 votes. The new votes gave Prosser a 7,316 vote lead.

Nickolaus' revelation sparked questions about fraud in Waukesha County. Nickolaus worked for Prosser when he was in the Assembly, and the county board had criticized her handling of past elections and a lack of oversight in her operations. Spurred by the election results, the state Government Accountability Board has launched an investigation into her practices.