The liberal candidate in Wisconsin’s hard-fought State Supreme Court race this month prevailed in voting by mail by a significant margin, upending years of study showing little advantage to either party when a state transitions from in-person to mail voting.

The gap suggests that Democrats were more organized and proactive in their vote-by-mail efforts in an election conducted under extraordinary circumstances, with voters forced to weigh the health risks of voting in person against the sometimes unreliable option of requesting and mailing in their ballots. Still, it is likely to add to the skepticism President Trump and Republicans have expressed about mail voting, which they worry would increase Democratic turnout at Republicans’ expense.

The liberal jurist, Jill Karofsky, performed 10 percentage points better than her conservative opponent in votes cast by mail than she did in votes cast at Election Day polling places, a gap that powered a surprising 11-point victory over all in a state both parties view as crucial to winning November’s presidential election.

The voting data, collected by The New York Times from 27 Wisconsin municipalities that segregate ballots cast on Election Day from those sent by mail, shows that Judge Karofsky’s advantage in mail ballots over the conservative incumbent, Justice Daniel Kelly, was consistent across communities of varying size, geography and partisan lean. In a state with little history of voting by mail, more than 1.1 million of 1.55 million votes cast came by mail.