Wisconsin’s public-sector unions hope to exact revenge against Gov. Scott Walker in tomorrow’s supreme court election for passing legislation curtailing their collective bargaining rights.

The law — currently under court injunction — inevitably will find its way before the state’s high court, and many observers on both sides of the issue see the election as a referendum on how the court should rule on the law.

Most judicial races go largely unnoticed, but unions and other liberal groups have sought to capitalize on anger over the collective bargaining law to oust incumbent Republican Supreme Court Justice David Prosser and “get even” with Walker this year. Who wins or loses will decide the makeup of the Wisconsin supreme court for the next decade and whether it has a conservative or a liberal majority.

Prosser’s opponent Democrat Anne Kloppenburg, a state assistant attorney general, has implicitly signaled her willingness to vote in favor of the unions should she topple Prosser.

“This is for all the marbles,” Charlie Sykes, a prominent conservative talk-radio host in Milwaukee, told National Review. “Scott Walker could survive losing the state senate. But it would be devastating if he were to lose in the supreme court. If Prosser loses, almost everything that Walker enacted could be overturned.”

Conservatives currently hold a 4-3 majority on the Wisconsin high court, and a letter from a Milwaukee American Federation of Teachers local declares “a Kloppenburg victory would swing the balance [on the court] to our side. A vote for Prosser is a vote for Walker.”

And the liberal Greater Wisconsin Committee has sought to drive this comparison home on its Prosser Equals Walker website, noting that Walker and Prosser voted the same way 95 percent of the time when they both served together in the state legislature in the mid-1990s.

Unions have charged that Prosser, who has served on the court since being appointed by former Gov. Tommy Thompson in 1998, has politicized the court by ruling against union interests and in favor of business.

“Prosser’s rulings as a justice clearly show his commitment to Scott Walker’s brand of scorched-earth politics against working families,” Stephanie Bloomingdale, says secretary-treasurer of the Wisconsin State AFL-CIO.

Pro-Prosser forces conversely have sought to paint Kloppenburg as underqualified for the state’s highest court because she has never been a judge, but their advertising has failed to keep her from gaining on the incumbent in the polls.

Close polling is never good for an incumbent state supreme court justice going into a retention election, considering that most incumbents usually coast to easy re-elections.

Conservatives worry that a Prosser defeat will result in a more activist, left-wing court. Indeed, prior to 2009 it was among the country’s most liberal court.

A spokesman for the pro-Prosser Wisconsin Manufacturers & Commerce (WMC) described the current conservative plurality on the court as a “rule of law” majority that could be set aside should Prosser lose.

A liberal court led by Chief Justice Shirley Abrahamson likely would block Walker’s effort to curtail union power or to preserve the tort-reform legislation he signed earlier this year. Abrahamson has a history of opposing tort reform, such as in 2005 when she voted with the majority to overturn the state’s non-economic malpractice liability cap by a 4-3 margin.

“Not only are public-employee unions attempting to choose their court, they are doing so by making an electoral issue of the very matter that the court will be asked to decide. There are reasons that we don’t hold votes on pending court cases,” Marquette University Professor Rick Esenberg writes in National Review Online. “They are rooted in due process and the rule of law. But in a world that chooses ‘any means necessary,’ these are mere inconveniences. It is time, after all, to ‘get even.'”

The election has received significant attention outside of Wisconsin, with national figures such as former Alaska Gov. Sarah Palin throwing her support behind Prosser because it has been seen as having nationwide ramifications for union power and the tea party’s effort to cut spending.

Millions have been spent on the race, with much of the money coming from outside the state.

The liberal Greater Wisconsin Committee has spent $993,000 against a combined $1.16 million that has been spent by groups on the right including the Wisconsin Manufacturers & Commerce (WMC), Club for Growth, Americans for Prosperity, Family Research Council Action, and Citizens for a Strong America. Tea Party Express has spent a further $200,000 on an ad painting Kloppenburg as a puppet of union bosses.

The contest could have a political impact that goes beyond tomorrow’s election, and not only because how it might influence supreme court’s deliberations over the collective bargaining law.

A Prosser win could potentially make it politically harder for the unions and their Democratic allies to recall several state senators who voted for the law and potentially recall Walker himself next year, when he is eligible.

It is also being looked at as a national gauge over how much the collective bargaining law has energized Democratic voters, or how resolved Republicans are in reining in union power.

State officials anticipate a 20-percent voter turnout, which means voter enthusiasm will determine the election’s outcome. Momentum would seem to favor the unions.