The election took place last week, before the Vermont senator left the 2020 race and endorsed Biden. The former vice president will likely face President Donald Trump in the 2020 general election. The state faced backlash for moving forward with in-person voting as the coronavirus pandemic spread, risking voter safety. Multiple other states delayed their primaries.
The state supreme court last week blocked Democratic Gov. Tony Evers' executive order to postpone in-person voting until June. It said he did not have the authority to move the election date on his own.
Then, the U.S. Supreme Court reversed a lower court order to extend the deadline to file absentee ballots, in a separate case filed before Evers' action. Even so, the court's decision did not change one remnant of the legal tug of war: Wisconsin counties did not report results until Monday.
With 99% of results in, Biden led Sanders by about a 63% to 32% margin.
Biden became the apparent Democratic presidential nominee when Sanders dropped out of the race on Wednesday. Biden will win at least 54 pledged delegates from Wisconsin, while his former rival Sanders will come away with at least 24, according to NBC.
The haul brings the apparent nominee's national total to 1,288, versus 942 for the senator.
Sanders has said he will remain on the ballot in the states where he already filed to appear, in order to rack up delegates and influence the party platform at the Democratic National Convention in August.
Meanwhile, liberal challenger Jill Karofsky declared victory over conservative state Supreme Court Justice Daniel Kelly in a closely watched contest. Trump backed Kelly and urged Wisconsin residents to vote for him last week, even as his administration discourages large public gatherings.
"Although we were successful in this race, the circumstances under which this election was conducted were simply unacceptable, and raise serious concerns for the future of our democracy," Karofsky said in a statement as results came in. "Nobody in this state or in this country should have been forced to choose between their safety and participating in an election."
If Karofsky wins, the court's conservative majority gets cut to 4-3. She would help to decide a fight over removing up to 209,000 people from voter rolls in a state that will play a major role in deciding the next president.