The Missouri Supreme Court on Thursday blocked a Republican-drawn new congressional map from being used in November’s midterm elections, dealing a blow to the party’s odds of maintaining its narrow U.S. House majority.

Read more EU joins U.S. sanctions push on Iran as South Korea weighs Hormuz deployment

The ruling could return longtime Democratic U.S. Representative Emanuel Cleaver to the House, after his Kansas City-based district was dismantled under the redrawn map.

The court found the state’s Republican secretary of state, Denny Hoskins, improperly rejected an effort to put the new map to a voter referendum before it could take effect.

Read more Trump-promoted Freedom Fuel expands to Detroit as lawsuit over supplier’s unpaid fuel heats up

Republican lawmakers had installed the new map as part of a broader campaign backed by President Donald Trump to redraw district lines to favor the party’s candidates.

Some Democratic states responded with their own redistricting plans. But Republicans eventually secured an advantage after a U.S. Supreme Court ruling permitted several conservative Southern states to eliminate districts with significant Black populations.

Read more Automakers urge Congress to permanently ban Chinese connected vehicles in U.S.