A crush of mail-in ballots, security concerns and an army of lawyers maneuvering ahead of Tuesday's voting are testing Minnesota's election system like no other election before.

State officials already navigating the pandemic have been called on to protect the integrity of the election, defend face mask requirements and guard against possible acts of voter intimidation.

Record numbers of early mail-in ballots also have sparked legal challenges in Minnesota and across the nation, culminating in a series of federal court rulings invalidating extended deadlines that were intended to make voting easier amid the spread of the coronavirus.

Among the latest to weigh in was the Eighth Circuit U.S. Court of Appeals, which ruled Thursday — five days ahead of the election — that Minnesota officials must set aside ballots received after Nov. 3, opening the way for potential legal challenges to a new state rule counting ballots received up to a week after the election.

The ruling prompted a scramble by state officials warning the public to ignore their past instructions and vote by Election Day, preferably in person.

"There will be more time later for expressions of disappointment," Secretary of State Steve Simon said soon after the ruling, which came in response to a Republican lawsuit. "For now, our focus has to be very clear and that is on the voters of Minnesota. We have to make sure that every legally cast ballot is counted. Period. That's the mission, from here through Tuesday."

On Friday, Eric Schuck and his fiancée dropped their ballots off at the early voting location at Brooklyn Center City Hall. Schuck, 34, said Thursday's court ruling made the trip to vote early more urgent.

"Even what they send you says you have the seven days so it was a surprise," Schuck said. "We just had to come out here and get it done now."

State officials also have been forced to fend off legal challenges to Gov. Tim Walz's face mask mandate at the polls. A new petition by a conservative group was presented Friday to the U.S. Supreme Court.

The legal wrangling over absentee ballots grew out of a broader attack on mail-in voting by President Donald Trump and his GOP allies, forcing local officials in Minnesota and elsewhere to respond to what they see as unsubstantiated suspicions of widespread fraud.

Those suspicions, in turn, have sparked unprecedented efforts by the Trump campaign to marshal an "army" of poll watchers — including some 3,000 in Minnesota. That has led to officials' concerns about interference or confrontation for the more than 1 million voters who are expected to cast their ballots in person on Tuesday.

Fueling those concerns were recent reports of private recruitment efforts for ex-special forces operators to work around polling places in Minnesota to protect against "antifas," an idea that was abandoned after a challenge by Attorney General Keith Ellison.

An election year overshadowed by the pandemic also has been marked by the high emotions that followed the police killing of George Floyd in Minneapolis, an event that led to civil unrest and a national debate over police and race. It also became the catalyst for a flurry of GOP campaign messages focused on law and order, including poll security.

For local officials tasked with managing votes, the pandemic had already created new stress points. It meant stocking up on personal protective equipment, making sure polling places can accommodate social distancing recommendations and — most important — that their citizens are aware of their options for casting their ballots.

"That's been one of our goals, to field every call we can, respond to every e-mail we can and run a next-day turnaround when it comes to [ballot] applications being processed and mailed out so we can cut down on uncertainty for voters — many of whom are voting in a different way for the first time," said Paul Linnell, the elections manager in Anoka County, which has already processed twice as many absentee ballots as in all of 2016.

As of Friday, Simon's office said that nearly 2 million Minnesota voters had requested absentee ballots. Of that total, more than 388,000 ballots had yet to be returned. Under the new court ruling, those ballots could be subject to further court action and not counted if they are not received by 8 p.m. on Election Day.

The rush to vote has not just been in the Twin Cities. Western Minnesota's Lac qui Parle County, which Trump carried in 2016, has seen one of the state's largest increases in early voting. Auditor-Treasurer Coordinator Jake Sieg said the spike might be related to the number of mail-only precincts in the largely rural county. In 2016, five of 29 precincts voted entirely by mail. This year, that's increased to 24. As the county began mailing ballots to voters' homes in mid-October, his office saw an uptick in questions from voters who "wanted to receive and return their ballots to us as soon as possible."

"This didn't happen in past elections," Sieg wrote in an e-mail.

Officials have also seen a surge in interest in Pipestone County, where 19 of the 22 precincts are mail-only. Activity at in-person precincts has tripled since 2016, according to county Auditor Tyler Reisch.

Based on what he's seen so far, Reisch feels confident about Election Day going smoothly. Unlike in the August primary, he said he hasn't gotten any official complaints about people not complying with the state mask mandate. He's reminded staff to enforce those rules at all voting sites.

But in a time of deepening political divisions, concerns about protecting voters — and the counting process — have become paramount.

In an unprecedented move, Walz recorded a video last week with former Govs. Mark Dayton, Tim Pawlenty and Jesse Ventura urging civility and patience around the election. Walz also joined Simon and Attorney General Keith Ellison in a forceful statement assuring voters of their rights to vote "safely and securely."

"No one may intimidate or interfere with you inside or outside a polling place. That means no one, from the President of the United States, to military, law enforcement, and agents of the government on down," Ellison said. "As Attorney General, I do not expect to have to enforce these laws. But I will not hesitate to enforce them."

Simon and Ellison also sounded the alarm amid reports that the Minneapolis police union put out a call to retired officers to serve as the Trump campaign's "eyes and ears" in what it deemed "problem areas" of the cities.

Minnesota law allows only for a single "poll challenger" per polling place to be appointed in writing by each major political party. "Unless they are the one and only designated person in writing by a political party, you can't just show up at a polling place purporting to be someone's eyes and ears," Simon said. "That's not the way it works and it's not the way it will work."

Federal authorities also are on the lookout for crimes such as intimidation, ballot-box stuffing or examples of people photographing or videotaping voters under the pretext of trying to uncover illegal voting. "I really believe strongly that Minnesotans are good, honorable people and I believe strongly that we will be able to see at the polls people being able to go in and not be intimidated," said Minnesota U.S. Attorney Erica MacDonald.

Federal intelligence officials also have been partnering with Simon's office to guard against the hidden threats of cyberattacks and disinformation campaigns around the 2020 election. But that is one area where officials feel they have met the challenge. Said Simon: "Our system is as of this moment untouched and unharmed."

Staff writer Zoë Jackson contributed to this report.

Stephen Montemayor • 612-673-1755

Twitter: @smontemayor

Torey Van Oot • 612-673-7299

Twitter: @toreyvanoot