This Wisconsin Court Race Is Highly Partisan. It Wasn’t Always That Way.

Today’s election in Wisconsin will be closely watched for its impact on the partisan makeup of the state’s top court, with abortion rights and election rules frequent topics of the campaign. The contest between Daniel Kelly, a conservative former state Supreme Court justice, and Janet Protasiewicz, a liberal Milwaukee County judge, is set to be one of the most consequential — and expensive — elections in the country this year.

Judicial elections in Wisconsin are officially nonpartisan, but the races have become increasingly political. While it used to be common for voters to cast ballots for judges with whom they weren’t ideologically aligned, Democratic counties now heavily favor the liberal judicial candidates and Republican counties the conservative ones.

The trend has been turbocharged in recent years as partisan polarization has grown nationally and as overt partisanship has crept into the dialogue among candidates for the court.

It wasn’t always this way. In the 1980s and 1990s, races were largely seen as less partisan and more swayed by endorsements from leaders in the legal and law enforcement community, according to Charles Franklin, the director of the Marquette University Law School Poll. He has studied the relationship between the ideological voting patterns in state Supreme Court races and presidential races.

“Supreme Court races at the time seemed to be about who had more endorsements from sheriffs and prosecutors than anything else,” he said.

While many candidates during the 1980s, 1990s and early 2000s had discernible ideological leanings, there was almost no relationship between electoral support for judicial candidates and presidential candidates of the corresponding political party. A notable example is Dane County, a longtime Democratic stronghold that is home to the University of Wisconsin at Madison. In 2000, a majority of voters in Dane County voted for Diane Sykes, a conservative judicial candidate, while also voting for Al Gore, the Democratic candidate for president.

Partisanship began creeping into races over the next decade. In a particularly vicious 2008 campaign, the conservative candidate, Michael J. Gableman, ran TV ads falsely accusing his opponent, the only Black justice on the state Supreme Court, of securing an early release of a rapist who was also Black. Mr. Gableman won by a narrow margin. After leaving the bench, he led a partisan inquiry into whether there was election fraud in Wisconsin during the 2020 presidential election.

But the races took on a more decidedly partisan tenor after the election of Scott Walker, a Republican, as governor in 2010. He pushed to pass a law that weakened public sector unions, leading to a particularly acrimonious moment in Wisconsin politics and an unsuccessful attempt to recall him. The Supreme Court race in 2011 was widely seen as a referendum on Mr. Walker’s policies. David Prosser, a conservative candidate, narrowly won the election, which was decided by 7,000 votes and required a recount. That race was also one of the first times in the state that ideological voting patterns in a judicial race nearly perfectly mirrored partisan votes of the most recent presidential election.

A 2015 change to state campaign finance laws ushered in vastly greater political spending by allowing unlimited donations to political parties. Parties could transfer large sums to the candidates, and increased coordination with outside groups was allowed. This year’s race will shatter spending records for judicial contests, with spending by candidates and outside groups reaching three times as high as any previous contest.

This election is poised to be the most politically aligned to date, Mr. Franklin said, citing “rising money, rising ideological signals, rising links to partisan voting.”

“This election is more of all these things,” he added. “A lot more.”

If the 2011 contest was seen as a referendum on Mr. Walker, today’s is seen by many as a referendum on abortion and whether the issue will continue to animate voters in the state. The winning candidate could be the deciding vote later this year when the court reviews the 1849 trigger law that has made abortion in the state a felony except to save the life of the mother. The law took effect after Roe v. Wade was overturned. Judge Protasiewicz has been outspoken in her support for maintaining abortion access, while Justice Kelly has been less explicit about his views on the issue, though he received endorsements and donations from anti-abortion groups.

Mr. Franklin sees the race as a test of the degree to which Wisconsin voters embrace the more explicitly partisan discussion of “values” that has become a hallmark of Judge Protasiewicz’s campaign.

“If Protasiewicz wins, it will demonstrate that campaigning openly on policy values can connect with voters in judicial elections,” he said. “If she loses, there will be tremendous second-guessing.”

Reid J. Epstein contributed reporting.