Early on, Prosser was widely expected to easily win re-election, given the advantages of incumbency in terms of fundraising, name recognition, and the organizational backing of the state business establishment and Republican Party in the nominally non-partisan race. However, the widespread protests against Gov. Scott Walker's anti-public employee union legislation quickly turned this into a proxy political battle, and unions brought a late but very energetic effort on Kloppenburg's behalf in an effort to defeat Prosser, a former Republican state Assembly Speaker.
Wednesday, April 6, the day after the election, Kloppenburg declared victory on the basis of Associated Press figures showing 100% of precincts reported, with Kloppenburg enjoying the very narrow lead of 204 votes out of nearly 1.5 million.
Then that Thursday, as counties were conducting the official canvass to check for errors in their election night spreadsheets that were reported to the media, Waukesha County Clerk Kathy Nickolaus (R) announced the discovery of un-tabulated votes from the city of Brookfield -- giving Prosser a net gain of over 7,000 -- saying that her own error had resulted in them not being properly imported and saved into the county's database.
"I'm thankful that this error was caught early in the process and during the canvass," Nickolaus said at her press conference at the time.
A month ago, shortly before Kloppenburg requested the recount, the GAB released a statement that its study of the vote numbers in Waukesha County found that the totals checked out on the ballot-scanning equipment and other documentation from the municipalities.