The slim margin between Wisconsin Supreme Court Justice David Prosser and his challenger, JoAnne Kloppenburg, has grown slightly in favor of the incumbent as late election numbers are tallied.

But the race that reflected Wisconsin's fight over union rights is still too close to call Wednesday morning. With 99 percent of precincts reporting, conservative-leaning Prosser is leading Kloppenburg by 835 votes. Final, official results could vary and a recount appears likely.

The race highlights the divide in the state over Republican Gov. Scott Walker's collective bargaining law, which would strip public workers of nearly all their union rights. The issue, which could ultimately be decided by the state Supreme Court, has propelled the relatively unknown Kloppenburg into prominence and heightened voter interest in the election.