The Democratic-backed candidate for Wisconsin Supreme Court defeated a challenger endorsed by US President Donald Trump and billionaire Elon Musk, touting her victory as a win against powerful interests and cementing a liberal majority for at least three more years.

Susan Crawford, a Dane County judge who led legal fights to protect union power and abortion rights and to oppose voter ID, stood on stage surrounded by the court's four current liberal justices and celebrated her win as a victory for democracy while also taking a dig at Musk.

“Growing up in Chippewa Falls, I never could have imagined that I would be taking on the richest man in the world for justice in Wisconsin,” Crawford said. “And we won.”

Musk and groups he backed had spent more than US$21 million in an effort to defeat Crawford. Musk even traveled to Wisconsin two days before the election to personally hand over US$1 million checks to two voters.

“Today Wisconsinites fended off an unprecedented attack on our democracy, our fair elections and our Supreme Court,” Crawford said in her victory speech.

“And Wisconsin stood up and said loudly that justice does not have a price, our courts are not for sale.”

Crawford defeated Republican-backed Brad Schimel in a race that broke records for spending, was the highest-turnout Wisconsin Supreme Court election ever and became a proxy fight for the nation’s political battles.

Musk was silent on his X platform in the wake of Crawford’s victory, reposting a message about Vietnam and tariffs but nothing on the Supreme Court contest.

Trump, Musk and other Republicans lined up behind Schimel, a former state attorney general.

Democrats including former president Barack Obama and billionaire megadonor George Soros backed Crawford .

The first major election in the country since November was seen as a litmus test of how voters feel about Trump’s first months back in office and the role played by Musk, whose Department of Government Efficiency has torn through federal agencies and laid off thousands of workers.

Musk traveled to Wisconsin on Sunday to make a pitch for Schimel.

Crawford was beating Schimel by more than eight points, based on unofficial results.

Turnout exceeded 52 percent of the voting age population, topping the record set in 2023 of nearly 40 percent.

Spending was on its way to surpass US$100 million.

Schimel told his supporters he had conceded to Crawford, leading to yells of anger. One woman began to chant, “Cheater, cheater!”

“No,” Schimel said. “You’ve got to accept the results.”

The court can decide election-related laws and settle disputes over future election outcomes.

Crawford embraced the backing of Planned Parenthood and other abortion rights advocates, running ads that highlighted Schimel’s opposition to the procedure.

She also attacked Schimel for his ties to Musk and Republicans, referring to Musk as “Elon Schimel” during a debate.

Schimel’s campaign tried to portray Crawford as weak on crime and puppet of Democrats who, if elected, would push to redraw congressional district boundary lines to hurt Republicans and repeal a GOP-backed state law that took collective bargaining rights away from most public workers.

Voters in Eau Claire seemed to respond to both messages. Jim Seeger, a 68-year-old retiree, said he voted for Schimel because he was concerned about redistricting.

Jim Hazelton, a 68-year-old disabled veteran, said he had planned to abstain but voted for Crawford after Musk, whom he called a “pushy billionaire”, and Trump got involved.

“He’s cutting everything,” Hazelton said of Musk.

“People need these things he’s cutting.”

Crawford’s win keeps the court under a 4-3 liberal majority, as it has been since 2023. A liberal justice is not up for election again until April 2028, ensuring liberals will either maintain or increase their hold on the court until then.

Crawford thanked each of the current liberal justices and hugged each of them after her win. One of the four is retiring, creating the open seat she won.

The court likely will be deciding cases on abortion, public sector unions, voting rules and congressional district boundaries.

Who controls the court also could factor into how it might rule on any future voting challenge in the perennial presidential battleground state, which raised the stakes of the race for national Republicans and Democrats.

Trump endorsed Schimel just 11 days before the election.

Last year the court declined to take up a Democratic-backed challenge to congressional lines, but Schimel and Musk have said that if Crawford won, the court would redraw congressional districts to make them more favorable to Democrats.

In Milwaukee, 22-year-old college student Kenneth Gifford said he feels that Trump has done damage to American institutions and that Musk is trying to buy votes.

“I want an actual, respectable democracy,” he said. (AP)