The wildly fluctuating (and closely observed) Wisconsin state Supreme Court election changed again dramatically Thursday evening as incumbent Justice David Prosser gained some 7,500 votes, owing to a human counting error in Waukesha County, a Republican stronghold some thirty miles west of Milwaukee.

As a result, challenger JoAnne Klopenburg now trails by some 7,000 votes.  Unofficial returns on Wednesday gave Klopenburg a lead by some 200 votes, but that margin had been narrowed to 40 by Thursday afternoon.  The uncounted votes--nearly 15,000 in all--were found as officials were conducting state-wide canvasses.

In describing how this happened, the Milwaukee Sentinel Journal reported that:

Waukesha County Clerk Kathy Nickolaus said Thursday that she failed to save in her computer and consequently report 14,315 votes cast in the city of Brookfield, omitting them entirely in an unofficial tally released after Tuesday's election. The new totals give 10,859 more votes to Prosser from Brookfield and 3,456 more to Kloppenburg, she said.

At a press conference following the discovery, Nickalaus, her voice wavering, said:

I'm thankful that this error was caught early in the process. This is not a case of extra ballots being found. This is human error which I apologize for, which is common.

While this may sound suspicious to some, the reigning Democrat on the Waukesha County Board of Canvassers has blessed the recount:

We went over everything and made sure all the numbers jibed up and they did. Those numbers jibed up and we're satisfied they're correct.

Still, the bombshell discovery has rocked the state of Wisconsin and blown open what was a back and forth race that is widely viewed as a referendum on Governor Scott Walker's efforts to curb the collective bargaining power of the state's public unions.

And while the election is not yet officially over, Slate's Dave Weigel was willing to concede the victory to Prosser and dash any hopes that the incident might lead to a recount:

Canvassing continues, but margins higher than a couple hundred don't usually get overturned in elections like this. The reaction from conservatives has been immediate, high-voltage schadenfreude, mostly because JoAnne Kloppenburg had declared victory based on the AP count putting her up by 204 votes.

Eric Kleefeld of Talking Points Memo was more incensed, and his coverage including the following exchanges form the press conference with Nickolaus :

What would she say about accusations of fraud, a reporter asked?

"Well, we sat through an open, transparent meeting for the last day and a half. We sat with people from both sides of the aisle, and went through every tape number by number, and proofed those numbers, then proofed those numbers again. Anyone who saw that canvass could see what we were doing."

Nickolaus was asked when the problem was discovered. "when I was uploading the data from the e-night results to the state system so we could start our canvass at noon, yesterday," said Nickolaus.

If it was found yesterday, a reporter asked, why announce it only today? "We had to verify that. We had to verify those numbers, and that is what we were doing."