MADISON, Wis (Reuters) - The closely watched race for a seat on the Wisconsin Supreme Court remained too close to call on Wednesday with just 235 votes of the 1.4 million votes cast separating challenger and front-runner JoAnne Kloppenburg from incumbent David Prosser.

The election, the first statewide vote since Republicans passed controversial restrictions on the union rights of public workers, was seen by some political analysts as a referendum on that measure and the scope of the mandate the Republican Party can claim as a result of victories in last fall's elections.

The struggle over state union powers propelled Wisconsin to center stage in a wider national debate over collective bargaining and government spending.

With 99 percent of the precincts in the state reporting, Kloppenburg had garnered 739,589 votes to Prosser's 739,354, according to the Milwaukee Journal-Sentinel newspaper WTMJ-TV.

Prosser is a former Republican member of the state Assembly while Kloppenburg is an assistant state attorney specializing in environmental affairs, and was backed by Democrats and organized labor.

Prosser, who maintained a narrow lead throughout the night but then fell behind late Wednesday morning, said there was "little doubt" there would be a recount.

Charles Franklin, a political scientist at the University of Wisconsin, Madison said it appeared about 33 percent of registered voters went to the polls -- the most in any spring election in at least a decade. Typical turnout in such contests is about 20 percent.

The stakes were as high as the margin was narrow because a lawsuit challenging the anti-union measure pushed by Republican Governor Scott Walker is already in the courts and making its way to the state Supreme Court, where self-described judicial conservatives, including Prosser, hold a 4-3 majority.

Legal challenges associated with any recount -- involving votes that are counted or excluded -- could add to the growing litigation the deeply divided state faces, experts said.

Both sides tried to claim the dead heat as a symbolic victory.

Prosser, cast by Democrats and organized labor as a Walker ally who needed to be removed to send a signal to Republicans, called the campaign against him "the most difficult assault on a person's character in the whole history of the Wisconsin judicial system."

"We're still in this race," he said. "I've weathered the nuclear blast and I'm still standing."

But others saw the deadlock as proof Walker had overreached and predicted moderate Republicans would see the result as a warning.

"It turns out that Walker's continuing claims of a great silent majority out there supporting him was only a great silent 50 percent," said Mordecai Lee, a former Democratic legislator who now teaches government at University of Wisconsin, Milwaukee.

"The vocal opposition to his collective bargaining bill was equally the same size ... I don't think moderate Republican legislators will let Walker lead them off a cliff."

Franklin, who also co-developed the website, said, "the 50-50 split proves how evenly divided the state is over the Walker agenda. And the turnout shows how deep the feelings run."

The Brennan Center for Justice at the New York University Law School, which monitors campaign ad spending, said $3.5 million had been spent on TV ads in the campaign, making it the most expensive court contest in Wisconsin's history.

That reflected both the race's high stakes as well as the interest of outside groups that either backed or opposed Walker's measures and purchased so-called issue ads in the contest, not covered by campaign finance limits.

Walker has defended the anti-union measure, which eliminates most bargaining rights for public sector workers and requires them to pay more for benefits, as a needed fiscal reform required to help the state close a budget gap.

Critics saw the bill, which eliminates automatic deduction of union dues, as a Republican attack on the single biggest source of funding for the Democratic Party -- unions.

(Additional reporting by David Bailey; Writing by James B. Kelleher; Editing by Jerry Norton)

Source: Reuters US Online Report Domestic News