Democratic Gov. J.B. Pritzker signed Illinois’ new congressional district map into law Tuesday, formalizing political boundaries drawn to help Democrats in next year’s midterm elections, when Republicans are well positioned to win control of the U.S. House of Representatives.

The map, approved in October by Democrats who control the Illinois Legislature, was intended to eliminate two Republican-held districts and make elections easier for Democratic candidates, even with the state losing one congressional seat due to population loss. Democrats said the new map reflected Illinois’ diversity by adding a second predominantly Latino district and maintaining three predominantly Black districts.

In a prepared statement, Pritzker said those maneuvers were key in preserving the Illinois delegation’s minority representation in line with federal law barring discrimination based on race, color or membership in a protected language minority group.

“These maps align with the landmark Voting Rights Act and will ensure all communities are equitably represented in our congressional delegation,” Pritzker said.

Republicans and others criticized the new boundaries as heavily gerrymandered, or drawn to benefit the political party in power. As happened in the recrafting of state legislative districts, interest groups and activists, many aligned with Democrats on most issues, criticized the secretive process and the result.

The law Pritzker signed Tuesday creates “predetermined winners and losers in nearly all seventeen districts” and strips voters of ballot decisions with which they can hold politicians to account, said Madeleine Doubek, executive director of Change Illinois, which advocates map-drawing by politically independent commissions.

“Never before have Illinoisans seen such a brazen show of how corrosive politician-led redistricting can be for voters and communities across the state…,” Doubek said in a statement. “Gov. J.B. Pritzker signed a map mired in a process lacking transparency, putting partisan self-interests above the needs of people.”

Nationally, the GOP used gerrymandering in 2011 to build Republican advantages for the next decade, and the party is now in charge of the mapmaking process known as redistricting in more than twice the number of states as Democrats.

That made Illinois’ new map even more critical for Democrats, who control the U.S. House by a thin margin and go into 2022 at a disadvantage, as the party in the White House historically has fared poorly in midterm elections.

Illinois’ new map, which will be used for elections through 2030, is aimed at creating a congressional delegation of 14 Democrats and three Republicans, a change from the current 13-5 split. The political fallout was almost immediate.

GOP Rep. Adam Kinzinger — a critic of President Donald Trump who was one of 10 House Republicans to vote to impeach him — announced he wouldn’t seek reelection hours after the Illinois House and Senate approved the map.

Democrats had drawn Kinzinger into a heavily GOP district with Republican Rep. Darin LaHood, a Trump supporter. Kinzinger opted to pass on a difficult primary, saying he couldn’t focus both on his reelection and a larger political fight of opposing Trump’s influence on the Republican Party.

Democratic Rep. Marie Newman, who was drawn into a majority-Latino district with Rep. Jesus “Chuy” Garcia, said she would instead run for reelection in the district now held by Rep. Sean Casten. That sets up a bitter Democratic primary for the suburban Chicago district.

In southern Illinois, GOP Reps. Mike Bost and Mary Miller also were drawn into the same district, potentially leading to a Republican primary battle in the heavily conservative area.

AP Political Writer John O’Connor contributed from Springfield.