JEFFERSON CITY, Mo. (AP) — Missouri’s top election official has rejected a citizens’ petition seeking a statewide referendum on new congressional districts backed by President Donald Trump.

Supporters of the referendum had submitted hundreds of thousands of petition signatures in a bid to force a November election on a new U.S. House map approved by the Republican-led state Legislature. But Republican Secretary of State Denny Hoskins asserted Tuesday that the petition is unconstitutional because congressional redistricting plans cannot be subject to voter referendums.

A group backing the referendum effort has said it will challenge Hoskins’ decision in court.

Missouri was the second Republican-led state, after Texas, to respond to Trump’s call last year to redraw congressional districts to the GOP’s advantage in hopes of holding on to the party’s slim House majority in the midterm elections.

The new map, which is being used in Tuesday’s primaries, dramatically reshapes the Kansas City-based 5th Congressional District, held by longtime Democratic Rep. Emanuel Cleaver, by stretching it into rural central Missouri to give it a Republican tilt. Republicans already hold six of Missouri’s eight congressional seats and hope to gain another under the new map.

Missouri’s redistricting plan has faced lots of litigation

People Not Politicians, the group sponsoring the referendum drive, submitted more than 300,000 signatures to the secretary of state’s office in December. Local election officials reviewed the signatures’ validity over the ensuing months and approved well more than the roughly 111,000 needed to qualify for the ballot.

But Hoskins waited until the last day allowed under state law to announce his decision about the referendum — a move that let the new districts be used in the meantime.

Hoskins had long signaled that he was likely to reject the referendum. He asked a federal court last fall to block the referendum petition from being submitted, arguing that congressional redistricting is not subject to a referendum under the U.S. and Missouri constitutions. A judge dismissed the lawsuit as premature, noting in a December ruling that Hoskins had the authority to reject the petition himself if he thought it was unconstitutional.

When Missouri candidates began filing for office in February, Hoskins said they were doing so under the new districts and told The Associated Press that “the referendum process was never meant to be used for redistricting.”

If Hoskins is wrong, and a court orders him to place the redistricting referendum on the ballot, it’s unclear what that means for the 2026 elections. Would candidates who win Tuesday’s primaries be allowed to continue running under the new districts in November while voters simultaneously decide whether those districts can be used in future elections? Would candidates run in different districts for the general election than were used in the primaries? Or would courts order a do-over for the congressional primaries using the state’s prior congressional districts?

Missouri’s mid-decade redistricting effort already has been among the most litigated nationally, triggering about a dozen lawsuits over the past year.

Republicans are ahead in the national redistricting fight

Legislative voting districts typically are redrawn at the start of each decade, immediately after a census. But Trump’s call for Republicans to redraw districts to their advantage led to an unusual outbreak of mid-decade mapmaking. The redistricting effort gained additional steam when the U.S. Supreme Court struck down a majority Black congressional district in Louisiana in late April, prompting Republicans in several Southern states to also redraw districts that had large minority populations.

All told, Republicans think they could win as many as 16 additional seats from new House maps enacted in eight states — Texas, Missouri, North Carolina, Ohio, Florida, Tennessee, Louisiana and Alabama. Democrats, whose counterattack faced several setbacks, think they could win up to six additional seats from new districts in California and Utah.

Voters ultimately will determine whether the new districts perform as intended. Even with redistricting, Republicans are facing headwinds. The president’s party historically has lost congressional seats in the midterms, and Trump’s poor approval ratings could provide an extra hurdle for Republican candidates.

Nearly 145 million people — about two of every five U.S. residents — live in states with new congressional districts for this election. Additional states are considering redistricting before the 2028 elections.

David A. Lieb, The Associated Press