MADISON, Wis. – Democrats and Republicans in Wisconsin were pushing Tuesday to get 320,000 outstanding absentee ballots returned by the close of polls on Election Day, after the U.S. Supreme Court refused to extend the deadline to receive and count ballots as Democrats had wanted.

"This is an all-hands-on-deck final push," said Ben Wikler, chairman of the Wisconsin Democratic Party.

The message is the same for Republicans who decided to mail in their ballots amid a surge in virus cases in Wisconsin. "If you do it absentee, do it now, do it quickly," said Andrew Hitt, chairman of the Wisconsin Republican Party.

It's not clear if the 5-3 ruling will benefit one side or the other in Wisconsin, which President Donald Trump won by fewer than 23,000 votes in 2016, said Barry Burden, a University of Wisconsin-Madison political science professor.

Trump campaigned in Wisconsin on Tuesday, and Democratic challenger Joe Biden is set to visit on Friday.

"The fact that Democrats are using mail voting more than Republicans suggests that the Biden campaign would be hurt more by ballots that come in late," Burden said.

However, since the appellate ruling nearly three weeks ago, Democrats have been working under the assumption that the deadline for returning ballots would be 8 p.m. on Election Day and have helped break the state record for returning absentee ballots.

As of Tuesday, more than 1.4 million ballots had been returned, including 352,000 that were cast early in person. That is 48% of the total Wisconsin votes cast in the 2016 presidential election. About 10 times more ballots have been returned by mail than in typical presidential elections.

Still, there were 320,000 outstanding ballots as of Tuesday, which amounts to 18% of the nearly 1.7 million absentee ballots requested.

The ruling setting the Election Day deadline for returning ballots means there will "definitely" be some that aren't counted, Burden said. In Wisconsin's April primary, some 80,000 ballots arrived after Election Day.