The Missouri Supreme Court unanimously ruled Thursday that the state’s newly drawn congressional map cannot be used in the November 2026 general election, restoring the congressional boundaries adopted following the 2020 census.

The decision comes after opponents of the new map submitted more than 300,000 signatures seeking to place the redistricting plan before voters in a statewide referendum. The court ruled that the referendum petition was legally sufficient and that the new congressional districts were effectively suspended once the petition was submitted.

The new map, approved by Missouri’s Republican-controlled Legislature and backed by President Donald Trump, was designed to reshape the state’s congressional districts and give Republicans a stronger opportunity to win an additional seat. Missouri currently has six Republicans and two Democrats in its eight-member U.S. House delegation.

The redistricting effort primarily targeted the Kansas City-based 5th Congressional District, which has long been represented by Democrat Emanuel Cleaver. Under the new boundaries, the district was expanded into more heavily Republican rural areas of the state, creating a significantly more competitive district.

The new boundaries were used during Missouri’s August primary elections. However, Thursday’s ruling means the results of those primaries will not determine the districts used for the November general election unless the new map is approved by voters.

Missouri Attorney General Catherine Hanaway, a Republican, said she plans to appeal the decision to the U.S. Supreme Court, calling the ruling a “constitutional crisis.” She argued that the decision represents an unprecedented intervention in congressional redistricting after a primary election.

The Missouri Supreme Court’s ruling also overturned Secretary of State Denny Hoskins’ rejection of the referendum petition. Hoskins had argued that a referendum could not be used to challenge a congressional redistricting law.

For now, the congressional map adopted after the 2020 census remains in effect for the November election. The new map could only return if Missouri voters approve it through the referendum process, leaving the state’s congressional races facing an unusual change in district boundaries between the primary and general elections.