A Wisconsin judge has ordered a purge of hundreds of thousands of voters from the swing state’s voter rolls ahead of the 2020 elections — dealing a victory to conservatives which could have an impact on the outcome of next year’s presidential election. Per the Milwaukee Journal Sentinel, Ozaukee County Circuit Court Judge Paul Malloy ordered the Wisconsin Elections Commission to invalidate the registrations of more than 200,000 voters who may have changed their addresses, rejecting the bipartisan agency’s effort to protect thousands of voters who might be purged by mistake.

For some context, President Trump won Wisconsin by fewer than 23,000 votes in 2016, and Democratic governor Tony Evers defeated Scott Walker by fewer than 30,000 votes in 2018. Also, Friday’s ruling seems likely to have a disproportionate impact on blue-voting parts of the state.

Back in 2017, the Wisconsin Elections Commission purged the registrations of 300,000 suspected “movers” who did not respond to an address-confirmation postcard within 30 days. But at least 7,000 voters had been erroneously identified, prompting confusion and complaints. In response, this year the WEC tried to avoid those problems by extending the deadline for the roughly 234,000 voters it mailed address-confirmation requests to. Using its authority under state law to create new rules with regards to maintaining the voter registration list, the WEC voted to give the affected voters until 2021 to respond to the request before their registrations would be purged.

Conservatives balked at the change, and the Wisconsin Institute for Law and Liberty ultimately sued to block it. It argued that the WEC was bound by statute to automatically remove the unresponsive voters’ registrations after 30 days, and that its attempt to extend the deadline was not lawful. WILL founder and attorney Rick Esenberg also downplayed the potential consequences of enforcing the deadline despite what happened in 2017 — highlighting how Wisconsin allows voters to register online and at the poll site on Election Day.

In the end, Judge Paul Malloy ruled against the WEC, insisting that only the state legislature had the authority to set a new timeframe for purging the voters. “I don’t want to see anybody deactivated, but I don’t write the legislation,” he said. And though WILL had only asked for an injunction, Malloy went so far as to directly order the commission to follow the statute and invalidate the registrations.

Doing so could affect a lot of voters. As of December 5, fewer than 19,000 Wisconsin voters had responded to the WEC’s 234,000 address-confirmation requests, and 60,000 mailers had been returned as undeliverable. An analysis by the Journal Sentinel found that 55 percent of the letters had been sent to municipalities that Hillary Clinton won in 2016. Twenty-three percent of the letters were sent to the heavily Democratic Milwaukee and Madison, where 14 percent of the state’s registered voters live.

Wisconsin Assistant Attorney General Karla Keckhaver asked Judge Malloy to stay his order, pending appeal, arguing that an immediate purge would “create chaos” and do “irreparable harm” to voters so close to February’s elections. Malloy denied the request, though he acknowledged that he didn’t know how the WEC would be able to carry out his order.

Malloy was appointed to the Circuit Court by Republican Governor Scott McCallum in 2002, then reelected three times by voters. (Judgeships are supposed to be nonpartisan.)

Both the WEC and the Wisconsin League of Women Voters say they plan to appeal Malloy’s ruling, which means the case is probably destined for the state’s Supreme Court, where conservatives hold a 5-2 majority. The court presents a major, longterm obstacle for Wisconsin Democrats, and the liberal advocacy group One Wisconsin Now has claimed that WILL’s lawsuit against the WEC is an attempt to help Republicans defend conservative Supreme Court Justice Dan Kelly, who is up for reelection in April.

Governor Tony Evers decried the WEC ruling on Friday, pointing to the narrow margin by which he won last year’s election, and calling out “another [GOP] attempt at overriding the will of the people and stifling the Democratic process.” Democratic Attorney General Josh Kaul responded by underlining the inevitable disenfranchisement, telling the Journal Sentinel that “any time people have to go through extra steps to vote, and certainly re-registering is a significant additional step, the result is that fewer people end up voting.”

Fewer people voting is also the likely goal, as Republicans’ so-called efforts to combat voter fraud have consistently shown — most recently in Georgia. In Wisconsin, researchers have estimated that strict voter ID laws may have discouraged many voters from voting in 2016 — with the intimidation being particularly effective on poor and black voters. And while some Democratic officials have exaggerated the impact of the GOP’s efforts in the state, there’s still plenty of evidence that voter suppression should be a far bigger concern than voter fraud in such scenarios.

The Wisconsin Institute for Law and Liberty, which backed the lawsuit against the state’s elections commission, is itself backed by the conservative Lynde and Harry Bradley Foundation, a Milwaukee-based organization which has spent hundreds of millions of dollars supporting right-wing causes around the country. Locally, the foundation was an important ally to Scott Walker, and it helped fund controversial voter-fraud billboards which appeared in Milwaukee in 2010 amid Walker’s run for governor. Each ad displayed three people behind bars — including two people of color — with a “We voted illegally” speech bubble and the bold-text warnings: “VOTER FRAUD is a FELONY” and “3 YRS & $10,000 FINE.” The billboards were widely criticized as an attempt at voter intimidation targeting racial minorities living an urban area, a motive the Bradley Foundation denied (two years later, when its link to the ads was finally brought to light.)

How much of an advantage President Trump gets from the Wisconsin voter purge, assuming Malloy’s ruling stands, remains to be seen. In the meantime, some are trying to use the news to strengthen Democrats’ resolve for the year ahead:

Apart from the potential impact on the leadership of the free world, the Wisconsin case has also led to criticism of the Electronic Registration Information Center, or ERIC, which is the national database Wisconsin and 28 other states use to analyze their voter rolls. ERIC matches voter data across multiple fields and then predicts which voters have moved or died. The League of Women Voters has argued that ERIC did not provide the “reliable data” required Wisconsin law requires the WEC to have in order identify a likely mover. Others have responded Friday’s ruling with additional criticism — including highlighting how algorithms can often have a built-in bias.

One of the election experts who helped create ERIC, David Becker, came to its defense on Saturday night. “No analysis is perfect,” the former director of the Pew elections division commented in a Twitter thread, “but ERIC is as close as you can currently get,” emphasizing that the system has also helped states add more than 30 million unregistered voters to their voting lists. He also endorsed the strategy that Wisconsin’s election officials have now been prevented from enacting. “[The WEC was] wise to try to wait to remove any records until 2021, as no data analysis is 100 percent perfect and this was the first presidential election in Wisconsin since they joined ERIC. Better to study this and confirm before removing records, even if it’s legal.”