CHICAGO (CBS/AP) — The two top-ranking elected Republicans in Illinois have filed a federal lawsuit asking a judge to overturn new state legislative maps created by Democrats without GOP input, arguing the redistricting process was unconstitutional.

Last week, Gov. JB Pritzker signed off on legislation creating those new maps, despite a campaign promise to veto any new legislative maps drawn by state lawmakers or their proxies.

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Pritzker said the new maps he signed “preserve minority representation in Illinois’ government in accordance with the federal Voting Rights Act.”

Illinois House Republican Leader Jim Durkin and Illinois Senate Republican Leader Dan McConchie filed a federal lawsuit on Wednesday, claiming the process the Democrats used to create the new maps was “arbitrary and discriminatory,” because it relied on American Community Survey population estimates, rather than full Census data, to determine the new boundaries of those districts.

“In its zeal to rush a plan through the legislature, the General Assembly drew the legislative districts in the Plan using population estimates derived from a survey rather than waiting a few months for the U.S. Census Bureau … to provide redistricting data containing official population counts from the 2020 decennial census,” their lawsuit states.

Democrats have argued they relied on ACS estimates because Census data won’t be available until at least August, weeks after the Illinois Constitution’s June 30 deadline for the General Assembly and governor to approve new maps. If that deadline had not been met, redistricting would have been left up to a bipartisan commission.

The lawsuit asks federal judge to either order the appointment of a “special master” to come up with new maps based on the 2020 Census, or to set up a bipartisan eight-member commission that would essentially give Republicans a 50-50 shot at drawing new maps.

Under the Illinois Constitution, if lawmakers don’t approve new legislative maps by June 30 the year after the decennial census, an eight-member bipartisan commission would be created and tasked with creating new legislative boundaries. If that commission can’t agree on a plan by Aug. 10, a ninth member, either a Democrat or Republican, would be picked at random to cast the tiebreaking vote.

In their lawsuit challenging the new maps created by Illinois Democrats, Durkin and McConchie argue the redistricting plan is unconstitutional, because it violates the equal protection guarantee of “one person, one vote,” and does not meet the requirement that legislative districts “be of equal, or at the very least, substantially equal population.”

They also argue the use of ACS population estimates is discriminatory, because it results in some populations being overcounted and others being undercounted.

“The Plan ensures that historically undercounted minority communities will continue to be underrepresented and lose their right to an equal vote in the legislature by foregoing the official census counts in favor of the ACS estimates,” the lawsuit states.

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McConchie claimed ACS population estimates never before have been used to draw up the state’s legislative maps.

“Today we are entering court on behalf of the thousands of families, small business owners, workers, and taxpayers who said they wanted an independently drawn map, not the one handed down by political insiders desperately clinging to power,” McConchie said in a statement. “We believe this is our best option to advocate for the 75 percent of voters who were refused an independent process and a map created with accurate data.”

The lawsuit names as defendants the top two Democrats in the General Assembly — Illinois House Speaker Emanuel “Chris” Welch and Illinois Senate President Don Harmon — as well as the Illinois State Board of Elections and its members.

In response to the lawsuit, Harmon’s office issued a statement from Illinois State Sen. Omar Aquino (D-Chicago), chair of the Senate Redistricting Committee, and Sen. Elgie Sims (D-Chicago) vice chair of the Senate Redistricting Committee.

“It is disappointing but not surprising Republicans would seek to strike down these new maps, which reflect the great racial and geographic diversity of our state. Throughout this process, they have done nothing but delay and obstruct efforts to ensure our communities are fairly represented, as seen by their refusal to even draft their own proposals. We stand by our work to ensure everyone has a voice in state government.”

Welch’s office provided a statement from Rep. Lisa Hernandez (D-Cicero), who chaired the House Redistricting Committee:

“As expected, the Republicans are doing everything in their power to block a map that reflects the true diversity of Illinois in hopes that they get a chance to single handedly draw a map for their political gain. Republicans in the House have done nothing but attempt to obstruct this citizen-driven process. They’ve staged charades for the media while spending well over $500,000 of taxpayer money out of their redistricting budget, but couldn’t even bother to submit their own proposals to be considered. This is just another disappointing waste of taxpayer dollars, but not at all surprising. We have full confidence in the maps passed by the legislature and signed by Governor Pritzker, and we will continue to review this lawsuit.”

Democrats have argued that the process was open, saying they took input at a series of public meetings that influenced how the boundaries were drawn. They also said there wasn’t time to wait for the census figures because maps must be completed by June 25. But that date is simply when they would lose complete control of the process.

When he was running for governor in 2018, Pritzker called for an independent commission to draw the lines and said he would veto politician-drawn maps. But in recent weeks, he noted that no commission had materialized and said he would veto any map that was “unfair.”

Political lines must be redrawn after each decennial Census to reflect changes in population and ensure the protection of voters’ rights. They must be compact, contiguous, and of equal population, among other things.

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CBS 2 Chicago Staff