A federal appeals court is weighing a challenge to Minnesota's one-week extension for counting mailed-in absentee ballots while elected officials and activists warn of confusion that could come from any changes so close to Election Day.

A three-judge panel of the Eighth Circuit U.S. Court of Appeals heard arguments Tuesday in a challenge to a recent rule change that permits state election officials to count ballots received until Nov. 10 as long as they are postmarked by Nov. 3.

Republican state Rep. Eric Lucero and GOP activist James Carson — both Minnesota GOP electors in the presidential race — have challenged a July state court agreement between Minnesota Secretary of State Steve Simon and a citizens group that filed suit earlier this year. Andrew Grossman, an attorney for Carson and Lucero, argued Tuesday that Minnesota state law and federal election law preempt the agreement and that votes received after Election Day could be challenged and disqualified.

The extension "threatens chaos come Election Day," Grossman added, arguing that the new deadline effectively keeps the polls open an additional seven days.

Simon has argued that blocking the extension days before the election could cause confusion. Nearly 2 million people have requested absentee ballots with the understanding that the ballots will be counted as long as they are postmarked by Tuesday. At latest count, more than a half million requested ballots have yet to be returned.

Assistant Attorney General Jason Marisam pointed out in a brief on behalf of Simon's office that a sudden change in the deadline would "potentially disenfranchise thousands of voters relying on their ballot instructions."

Responding to an earlier lawsuit by a citizens group this year, Simon agreed to extend the state's deadline for accepting and counting mail ballots from 8 p.m. on Nov. 3 to Nov. 10.

The plaintiffs in that case — the Minnesota Alliance for Retired Americans Educational Fund — cited the pandemic and a record surge in mail ballots. The agreement also waived a requirement for witness signatures on absentee ballots.

President Donald Trump's campaign and the Republican National Committee initially appealed Simon's agreement to the Minnesota Supreme Court, but later abandoned the effort with an agreement that it would not pursue any further court challenges to the extension.

Lucero and Carson then challenged the agreement in federal court on Sept. 22, three days after early voting began in the general election. Earlier this month, U.S. District Judge Nancy Brasel rejected their motion for an order halting the extension, finding that neither one had legal standing to bring the case. Brasel also wrote that reversing the extended deadline one month after early voting started would create confusion among voters who had been instructed on the extension for months.

Tuesday's arguments before the Eighth Circuit Court judges took place as the U.S. Supreme Court is ruling on similar extensions in key states such as Wisconsin, Pennsylvania and North Carolina.

The high court on Monday sided with Republicans in a 5-3 order that prevented Wisconsin from counting mailed ballots received after Election Day.

A lower court order had installed a six-day extension in the state.

That order, in which the court's three liberal justices dissented, came before Monday's U.S. Senate vote to confirm Trump's nomination of Judge Amy Coney Barrett to the Supreme Court. Barrett joined the court on Tuesday, solidifying a 6-3 conservative tilt.

Last week, Chief Justice John Roberts joined his liberal colleagues in preserving a Pennsylvania state court order that extended its absentee ballot deadline by three days.

Roberts voted the other way in the Wisconsin case, he later explained, because it had moved through federal courts.

Still, the latest rulings are prompting elected officials and advocates alike to urge Minnesota voters to drop off their ballots in person at election offices or other designated drop-off sites by 3 p.m. on Monday to avoid having their votes challenged or disqualified.

Even with the election one week away, the Eighth Circuit panel did not specify a timeline to render a decision.

Gov. Tim Walz told reporters Tuesday that he did not believe Minnesota's ballot deadline extension is in jeopardy. He likened arguments against the extension as "false innuendo" and "nothing more than a voter suppression tactic."

"I'm telling you, I've coached enough football, if you're complaining about the refs before the game starts, you're losing," Walz said.

Twitter: @smontemayor