Wisconsin voters on Tuesday chose one liberal and one conservative candidate to face off in a race to determine control of the state supreme court in what is likely the most important election of 2023.

Janet Protasiewicz, a liberal Milwaukee circuit court judge, will be on the ballot against Daniel Kelly, a conservative former supreme court justice, in the state’s 4 April general election. Protasiewicz, who received 46% of the statewide vote, and Kelly, who received 24% of the statewide vote, advanced from a four-member field that included Everett Mitchell, a liberal judge in Dane county, and Jennifer Dorow, a conservative judge in Waukesha county.

Conservatives currently have a 4-3 majority on the court, but if Protasiewicz wins, the balance of the court would flip.

That would have enormous impact in Wisconsin, one of the most politically competitive states in America that often determines the outcome of the presidential election. The court is expected to have a say in the near future on a range of major voting rights and abortion decisions.

In 2020, the state supreme court narrowly turned away a lawsuit from Donald Trump seeking to throw out votes. It is likely to weigh in on a range of election disputes ahead of the 2024 election in Wisconsin, where races are regularly decided by razor-thin margins. A shift in the balance of the court would also likely prompt a request asking the justices to reconsider striking down the state’s legislative maps, which are so severely gerrymandered in favor of Republicans, it is virtually impossible for Democrats to ever win control of the state legislature.

The court will likely ultimately decide whether the state’s 1849 abortion ban is legal. A shift in the balance of the court may also prompt another lawsuit asking the high court to consider striking down the state’s legislative maps, which are among the most gerrymandered in the country.

“Everything we care about is going to be determined by who wins this election,” Protasiewicz said in victory remarks on Tuesday evening.

“Never before has a judicial candidate openly campaigned on the specific intent to set herself above the law, to place her thumb on the scales of justice to ensure the results satisfy her personal interest rather than the commands of the law,” Kelly said in his victory speech.

The race is already projected to shatter the $10m spending record for a state supreme court race, which was set in 2020. There were nearly $7m in political ad orders placed in the primary, according to the Brennan Center for Justice, which is tracking that spending.

Spending in the race is expected to be dominated by outside groups. Fair Courts America, a Super Pac backed by GOP megadonor Richard Uihlein, has pledged millions in support of Kelly. The anti-abortion group Susan B Anthony Pro-Life America has also pledged six figures in support of Kelly. A Better Wisconsin Together, a liberal group, also spent nearly $1.8m so far, according to the Brennan Center’s database.