Kansas’s new congressional map will face a lawsuit in state court, the leader of a national Democratic group that’s supported legal fights over redistricting in other states promised Thursday.

Former U.S. Attorney General Eric Holder, chairman of the National Democratic Redistricting Committee, called the map gerrymandered and said a court challenge would come within a couple days.

“Republicans diluted voices of the most populous and diverse region of the state for partisan gain,” Holder, who led the U.S. Department of Justice under President Barack Obama, told reporters on a conference call.

A lawsuit has been widely anticipated, but Holder’s comments were the clearest signal yet that opponents of the Kansas map plan to push forward aggressively in state court. Part of their calculus is that a state Supreme Court where a majority of justices have been appointed by Democratic governors is their best chance.

Moreover, the Kansas Constitution contains an “equal protection” clause. Map opponents may argue that district lines dividing minority residents within Wyandotte County violates that provision.

The Republican-controlled Legislature on Wednesday completed its override of Democratic Gov. Laura Kelly’s veto of the GOP-drawn map, which divides Wyandotte County, the most racially and ethnically diverse county in the state, for the first time in 40 years. The 3rd Congressional District, currently held by Democratic U.S. Rep. Sharice Davids, is expected to be less Democratic under the map.

The map also moves Lawrence, a Democratic enclave, into the reliably-Republican 1st Congressional District, a largely rural district that encompasses the western half of the state.

The National Democratic Redistricting Committee says the organization and its affiliates have supported successful litigation in North Carolina, where the state Supreme Court overturned a GOP-leaning map, and in Virginia, where the state Supreme Court drew maps.

The increasing focus on state courts comes after the U.S. Supreme Court in 2019 took away the power of the federal judiciary to reject maps because of partisan gerrymandering. Racial gerrymandering remains illegal under federal law, but the Supreme Court on Monday halted a lower court ruling that Alabama must draw a new congressional map to increase Black voting power.

Republicans contend they haven’t racially gerrymandered the map. They note the 2nd Congressional District is more diverse under this map and that the 3rd District would have still leaned Democratic during the 2020 presidential election under its new boundaries.

Kansas Republicans have said they are confident about their chances in court. House Speaker Ron Ryckman, an Olathe Republican, said the map should be challenged in federal court, not state court and that the Kansas Supreme Court should decline to take the case.

“Based on what’s happened across the United States these types of maps are going to be upheld,” Ryckman said. “A lot of attorneys will make money trying but I’m pretty confident that it gets upheld.”

The Star’s Katie Bernard contributed reporting