WASHINGTON (CNN) -- Both candidates for a hotly contested state race in Wisconsin agree the campaign has become nasty, but that's about the only thing they agree on.
The incumbent has been accused of helping to free criminals, his opponent of being the beneficiary of political cronyism.
The two men are judges and the prize they seek is a 10-year term on the state Supreme Court. The election could set nationwide records for spending on a judicial race by the time votes are cast Tuesday.
Justice Louis Butler -- already on the high court after being appointed to fill a vacancy -- and Burnett County Circuit Judge Michael Gableman have traded partisan attacks, helped by hundreds of broadcast ads aired across the state, most funded by a host of independent advocacy groups.
"What's remarkable about this race is how dominant the outside groups have been," said J.R. Ross, editor at WisPolitics.com. "They've outspent the candidates themselves 10-to-1 on TV ads. They're essentially drowning out the messages of Butler and Gableman."
Ross said latest estimates show more than $3 million spent just on TV ads in the state's top three media markets: Milwaukee, Madison and Green Bay.
The stakes in Wisconsin and nationwide are high, and are fueling renewed calls for reform on how judges are selected. The 19 states that held state Supreme Court elections last year shattered previous campaign cycle spending records -- $34.4 million in all -- which have increased steadily in the past decade.
The idea of judges running for elected office may seem like a strange concept, but it is the law in 21 states that have some sort of contested system for top judges. Thirty states -- along with the federal system -- appoint their judges, often under a merit selection system in which the governor gets the final say.
All 21 states will hold elections for Supreme Court seats this fall, but the early race in Wisconsin is considered a political bellwether of the tenor and sway outside partisan groups will have on how these campaign will be run.
"Wisconsin is the current hot spot in the culture wars that have played in the courts in recent years," said Rebecca Kourlis, founder and director of the Institute for the Advancement of the American Legal System, which works to improve the civil justice system. "More and more money is being poured into these judicial races, more planning on how candidates position themselves for a political audience. These elections have simply gotten out of control."
Unlike some states, Wisconsin does not require candidates to list themselves by party. Butler was appointed to the state high court in 2004 by Democratic Gov. Jim Doyle. He runs on his judicial and life experience. The only African-American on the bench, Butler, 56, has been a longtime judge.
He was previously a public defender, and that is where the current attack ads have focused. His opponent ran his first TV commercial suggesting Butler's appellate defense of a child rapist led to the defendant's early release. But the man had, in fact, served his entire sentence.
A liberal activist group filed a complaint with the state election board, contending that ad was misleading.
A conservative group, Coalition for America's Families, ran its own spot criticizing Butler for writing an opinion overturning another rapist's conviction. The group also claimed he had "sided with criminals nearly 60 percent of the time," a statistic it has not substantiated.
Factcheck.org, a self-described "consumer advocate" for voters, called the ad "distorted." Gableman has since called on the coalition to stop the ads. The group did not return CNN's calls.
Gableman, also a longtime state judge, calls himself a judicial conservative. He is a former prosecutor and campaigns on a tough law-and-order agenda.
A left-leaning group -- Greater Wisconsin Committee -- ran an ad suggesting Gableman got his job only because of political payback. The ad implied the judge was named to his current seat after a $1,250 campaign donation to then-Republican Gov. Scott McCallum, who appointed him. The ad was attacked by a non-partisan state monitoring committee. McCallum denounced the group as well, saying Gableman is well-qualified for the bench.
Gableman is supported by a coalition of sheriff's and district attorneys, and Wisconsin Right to Life.
Butler has the nod from a number of judges, law enforcement groups and the state AFL-CIO.
"The balance of the court is stake here," said Ross, saying the seven-member high court is split nearly evenly along ideological lines, but tilts often to the liberal side. "What happens Tuesday will effect what happens for the next decade. It's an enticing opportunity, particularly for conservative groups -- to be able to toss out a sitting justice" who most experts say leans liberal. The last state high court incumbent to lose was in 1967.
Judicial elections were long the sleepy backwater of state politics. So why all the growing attention? Political and legal experts say uncertainty over how much money special interests can donate to legislators in various states is one factor. The focus on the courts also reflects the overall intensity and partisanship for state and federal elections.
The state said Friday only 20 percent of Wisconsin's voting age population is expected to show up at the polls Tuesday.
A study released last October by the non-partisan Annenberg Public Policy Center found people in states with no partisan elections for judges had a higher level of trust and confidence in the judiciary. But two-thirds of those surveyed also preferred electing judges directly to having them appointed. E-mail to a friend
All About Wisconsin • Elections and Voting