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A federal appeals court ruled Thursday that mailed-in ballots in Minnesota must be received by elections officials no later than Election Day and suggested voters consider other options for casting their ballots.

The 2-1 ruling – a win for the Republican challengers to the state’s plans – cuts off a weeklong window after Election Day where state officials had planned to receive ballots that had lingered in the mail. The court found the Minnesota secretary of state’s accommodation went against a state law that said ballots delivered by mail to elections officials after 8 p.m. on Election Day should be marked late.

“The Secretary’s instructions to count mail-in ballots received up to seven days after Election Day stand in direct contradiction to Minnesota election law governing presidential elections,” the ruling stated.

The 8th US Circuit Court of Appeals urged voters to consider voting in other ways, because the court has not yet decided if votes that come in via mail after Election Day are legal.

“Better to put those voters on notice now while they still have at least some time to adjust their plans and cast their votes in an unquestionably lawful way,” the appeals court said in its ruling.

Voters in Minnesota can turn in their absentee ballot at designated drop-off locations by 3 p.m. on Election Day. They can also go vote in person even if they have requested absentee ballots; voters can track their ballots online and if they haven’t been received by Election Day they are allowed to vote in person and their mail-in ballots will no longer count.

The appeals court said that the ballots received by officials after Election Day should be set aside separately from ballots that were received on time, and not counted.

The decision tackles absentee ballot deadlines in a battleground state a day after the US Supreme Court declined to wade into plans in Pennsylvania and North Carolina to continue to accept ballots after Election Day.

The Trump campaign had sided with cutting off the receipt of ballots by Election Day.

The decision on Thursday night potentially throws into chaos the plans of Minnesota voters who have not yet mailed their absentee ballots. It sets up the possibility those votes may not be counted if they are postmarked in the coming days.

In a news conference Thursday night, Minnesota Secretary of State Steve Simon said he didn’t know yet if the ruling would be appealed.

Simon noted that while ballots received after 8 p.m. on Election Day must be segregated, it is undecided whether those votes ultimately will count toward the election total. Election officials are still allowed to count but not tabulate ballots received after the deadline, so it is possible that there will be two final tallies: ballots that made it in before 8 p.m. and those that didn’t, he said.

As of Thursday evening, a little under 400,000 absentee ballots that had been requested by and sent to voters had not been received by election officials, Simon said.

“The consequences of this order are not lost on us,” the court’s opinion said. “We acknowledge and understand the concerns over voter confusion, election administration issues, and public confidence in the election. … With that said, we conclude the challenges that will stem from this ruling are preferable to a postelection scenario where mail-in votes, received after the statutory deadline, are either intermingled with ballots received on time or invalidated without prior warning.”

The appeals court sided with two of the Republican Party’s nominees for its Electoral College slate in Minnesota. The two electors challenged the Minnesota secretary of state’s decision to add a week for the state to receive ballots after Election Day.

US Sen. Amy Klobuchar, D-Minnesota, told voters to not mail in their ballots after the ruling.

“Because of LAST MINUTE ruling, Minnesota DO NOT put ballots in mail any more,” Klobuchar said on Twitter. “In the middle of a pandemic, the Republican Party is doing everything to make it hard for you to vote. Stand up for YOUR rights: Vote in-person or take mail-in ballot directly to ballot box.”

Minnesota Republican Party Chairwoman Jennifer Carnahan said in a statement that the party was pleased with the decision.

“We applaud the Eighth Circuit Court of Appeals for upholding the integrity of the election and affirming Election Day as November 3rd,” she said. “The pandemic has caused upheaval in many areas of life but hiding behind the pandemic to manipulate the election process is not democratic, and we appreciate that our laws and interpretation of those laws matter.”

Minnesota Gov. Tim Walz, a Democrat, in an appearance on CNN’s “Erin Burnett OutFront” slammed Republicans for bringing the case and bemoaned their praise of the decision.

“It speaks volumes when your goal is to make it more difficult for people to vote,” Walz said. “It probably speaks that they are not really happy with your policies, so here in Minnesota, we will still count all the votes, the system is still secure, those ballots will be segregated and I think this will obviously go up further through the judiciary to get a decision. But at this point in time, people can avoid all this by simply going and dropping their ballots off in person.”

This story has been updated with additional details.