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The Wisconsin Supreme Court on Monday afternoon shot down a last-minute election-eve push by the state’s governor to suspend in-person voting for the state's scheduled Tuesday primary due to health concerns amid the coronavirus pandemic.

The state's highest court -- which is controlled by conservatives -- ruled 4-2 that Gov. Tony Evers, a Democrat, lacked the authority to move the election on his own.

THE LATEST FROM FOX NEWS ON THE 2020 PRESIDENTIAL CAMPAIGN

Hours later, the U.S. Supreme Court struck down a federal district court judge's ruling allowing people voting by absentee ballots an extra week to return their ballots. The ruling by the high court broke along ideological lines, with the five appointed by Republicans overruling the four appointed by Democrats.

Evers previously had resisted delaying the election -- saying he didn't have the authority to move the date -- but on Monday he signed an executive order that would have pushed in-person voting for the April 7 contest to June 9.

The governor's order would have also directed the state's GOP dominated state legislature to meet Tuesday in special session “to address the election date.” The order stated that if the legislature doesn’t pass a bill moving the primary’s date, voting would have occurred on June 9.

Republican legislative leaders pushed back against the governor's move.

“We are immediately challenging this executive order in the Wisconsin State Supreme Court,” Speaker Robin Vos tweeted.

Hours before the ruling by the state's Supreme Court, Evers said "my hope is that the courts of Wisconsin will agree that this is an unprecedented moment in time and affirm that my action today is necessary to keep the people of our state safe."

Evers’ move came as Wisconsin was attempting to do what no other state has tried to do – hold in-person voting at polling amid the coronavirus pandemic – as most Americans huddle in their homes to avoid the spread of the deadly COVID-19 disease caused by the virus.

The governor's push came one day after mayors of some of Wisconsin’s biggest cities pleaded for a delay in the election.

In a letter to the state’s Department of Human Services, 10 mayors representing some 1.3 million residents warned that if in-person voting takes place on Tuesday, it would put “hundreds of thousands of citizens at risk by requiring them to vote at the polls while this ugly pandemic spreads.”

Hours before the governor signed his executive order, the state’s elections commission put out a list of 10 things voters should know before heading to the polls.

Among Monday’s guidance is a request to “keep your face-to-face interactions brief with both poll workers and other voters. We want to limit the risk for everyone in the process on Election Day.” And the elections commission noted that “curbside voting options are available” for those who are ill and need to vote.

With the state under a stay-at-home order, thousands of poll workers have indicated they wouldn’t be showing up on Tuesday, forcing many cities and towns to cut the number of polling stations. Milwaukee was down to just five polling sites from the original 180.

“Because of poll worker shortages, your polling place may have changed due to consolidation,” warned the elections commission, which urged voters to check the state elections website before heading out to vote.

The National Guard stepped in to provide some assistance, distributing hand sanitizer and other supplies to polling states across the state.

The governor’s primary-eve move came three days after he called for a special session of his state’s legislature to overhaul the Tuesday primary -- by allowing for an all-mail election, sending absentee ballots to every registered voter and pushing the deadline back until May 26 for ballots to be returned.

The request by Evers – who’s repeatedly highlighted that he doesn’t have the unilateral power to change the date of the election – was brushed aside by the Republican-controlled legislature. GOP leaders said the governor’s move came too late and that they had “grave concerns about election security” by allowing absentee ballots to be submitted beyond election day.

On Monday, GOP leaders noted, in challenging the latest order, that the governor has said he can't move the election on his own.

In Washington, the U.S. Supreme Court ruled that a federal district court judge exceeded his authority last week when he allowed for absentee ballots to be counted through April 13, one week after the scheduled date of the contest.

The judge was ruling on lawsuits seeking to delay the primary that were filed by the Democratic National Committee, state Democrats, and several voter advocacy groups. The judge declined to postpone the primary’s date, but did allow for absentee balloting to be extended for a week.

State Republican legislative leaders on Saturday joined the Wisconsin Republican Party and the Republican National Committee in appealing the ruling – which was mostly upheld by a federal appeals court judge – to the Supreme Court.

Democrats unsuccessfully urged the Supreme Court to deny the GOP push to mandate that all absentee ballots be returned by Tuesday night, arguing that tens of thousands of voters wouldn’t even receive their ballots by primary day.

The battle over the Wisconsin primary's seen as an appetizer in the bigger national fight over a push by Democrats for states to implement broader access across the country to absentee ballots and voting by mail.

Wisconsin residents have been urged for weeks to vote by absentee ballot, which already has led to a tidal wave of demand for vote-by-mail ballots. Election officials reported on Sunday that they received 1,268,587 absentee requests and that 1,256,474 absentee ballots had been sent to voters. They reported that 703,048 ballots had been returned.

Eighty-four Democratic nomination convention delegates are up for grabs in Tuesday’s presidential primary between clear front-runner Joe Biden and Sen. Bernie Sanders of Vermont.

But there’s a lot more at stake on Tuesday’s ballot for Wisconsin voters than just the presidential primary contest. There’s an important battle for a Wisconsin Supreme Court seat that could influence general election voting rules in the crucial presidential battleground state, as well as numerous mayoral contests including in Milwaukee, the state’s largest city.

Sanders called for postponing the primary.

"People should not be forced to put their lives on the line to vote, which is why 15 states are now following the advice of public health experts and delaying their elections. We urge Wisconsin to join them," the senator said in a statement on Wednesday.

While deferring to Wisconsin officials and declining to take a stance, Biden on Thursday said: “I think you could hold the election as well dealing with mail-in ballots and same-day registration.”

“I think it’s possible to do both, to have both more mail-in ballots” he added. “I think it could be done ... but that’s for them to decide.”

On March 17, Florida, Illinois and Arizona were the last states to hold presidential primaries. Since then, 15 states and Puerto Rico – which were scheduled to hold their primaries and caucuses in late March, April or May – postponed their contests or switched them to nearly entirely by mail or absentee ballot.

Fox News' Jennifer Girdon and Kelly Phares contributed to this report