A federal appeals court has blocked a preliminary injunction that would have prevented Illinois citizens from registering to vote at select polling locations on Election Day.

The U.S. Court of Appeals for the Seventh Circuit in Chicago on Tuesday stayed a lower court judge’s decision to temporarily block parts of SB 172.

The law, pushed by Democratic lawmakers and passed in 2014, allows citizens who live in the 20 counties with populations of at least 100,000 and/or counties of 100,000 or less with electronic poll books, to register to vote at their local polling places on Election Day.

Those challenging the law have until Thursday to submit an explanation to the court clarifying why their case should be expedited in time for the November 8 elections.

In August, the Crawford County Republican Central Committee and Patrick Harlan, a Republican candidate for the U.S. House of Representatives in the 17th Illinois Congressional District, filed a lawsuit in the Northern District of Illinois to have the law ruled unconstitutional.

Filed on behalf of the Liberty Justice Center, Harlan’s lawsuit lists the eight-member Illinois State Board of Elections board as defendants.

As the Chicago Tribune reported, the Illinois Policy Institute, a tax-exempt organization that is reportedly a donation recipient of Republican Gov. Bruce Rauner, founded the Liberty Justice Center in 2011.

Harlan’s lawsuit argued that the law created an “unfair, unequal system for Election Day voter registration” and that it disenfranchised people who live in 82 Illinois counties with populations of less than 100,000. The complaint alleged that rural areas in the state were more likely to have Republican majorities.

District Judge Samuel Der-Yeghiayan agreed, writing that the law “favors the urban citizen and dilutes the vote of the rural citizen.” He allowed the preliminary injunction against same-day voter registration at polling locations.

Progressive groups in the state, including the Just Democracy Illinois coalition, which supported the automatic voter registration bill that Rauner vetoed in August, opposed Der-Yeghiayan’s ruling, because they said it would hurt communities that have experienced voter suppression. Illinois Attorney General Lisa Madigan appealed that decision the same week.

Trevor Gervais, lead organizer for Common Cause Illinois, a member of the Just Democracy group, told Rewire in a phone interview that Common Cause and its allies were optimistic about the future of same-day registration at polling locations in the state.

If the injunction had not been blocked, citizens would be limited to registering at the headquarters of local election authorities on Election Day, the Chicago Tribune reported.

Common Cause characterized the lawsuit as a “troubling tactic to limit voter turnout during a crucial election year” in an emailed statement.

The group’s executive director, Brian Gladstein, added that more than 110,000 people registered to vote on Election Day last March.