FILE PHOTO: U.S. President Donald Trump speaks as he and Canada's Prime Minister Mark Carney (not pictured) meet in the Oval Office at the White House in Washington, D.C., U.S., October 7, 2025. REUTERS/Evelyn Hockstein/File Photo

By Joseph Ax

Dec 11 (Reuters) - The Indiana Senate on Thursday rejected a new congressional map that would have boosted Republican chances of keeping control of the U.S. House of Representatives in next year's midterm elections, dealing a blow to President Donald Trump's nationwide push to install more friendly maps.

The vote represented a rare rebuke to Trump by members of his own party, which he has largely ruled with an iron fist as president. The tally was 31-19 against, with more than half of Republican senators joining all 10 Democrats in voting against the bill despite a months-long pressure campaign from the White House aimed at the holdouts.

Trump had threatened to support electoral challengers to any Republican senators who refused to vote in favor of the map, calling several out by name in a series of hostile social media posts leading up to Thursday's vote.

The map, which passed the Indiana state House last week, would likely have given Republicans a 9-0 sweep of the state's U.S. House seats in next year's midterms, when control of Congress will be at stake.

The redrawn map would have reshaped the two districts currently held by Democrats, including by splitting the state's largest city, Indianapolis, into four districts, a move that Democrats have said will harm minority voters in particular.

Republican lawmakers who backed the law on Thursday urged other Republicans to pass the bill and help Trump's agenda in Congress, warning that a Democratic House would pursue dangerous policies.

In a fiery speech, Senator Chris Garten said nothing less than the future of the country was at stake. The sponsor of the bill, Mike Gaskill, suggested the "second U.S. Civil War has already begun."

Senator Spencer Deery, one of three Republicans who spoke out against the bill during the floor debate, acknowledged he also did not want to see Democrats win a House majority.

"But that isn't for me to decide, and it isn't for anybody in this body to decide either," he continued. "Living in a free constitutional republic means we empower voters to make those decisions, and we accept their will no matter what."

Redistricting typically occurs at the start of each decade to incorporate new U.S. Census data. But Trump ignited a nationwide battle this summer, when he successfully urged Texas Republicans to draw a new congressional map taking aim at five Democratic incumbents.

In response, Democrats in California proposed their own redrawn map intended to flip five Republican seats, a plan that was overwhelmingly approved by voters in November. Other states, both Republican- and Democratic-controlled, have initiated their own redistricting efforts.

Some state lawmakers have balked, however. Trump's push stalled in Kansas amid reluctance from some Republicans, while Democrats in Maryland are split on whether to advance a new map.

Democrats must flip only three Republican seats in the 435-member House next year to win a majority.

(Reporting by Joseph Ax; editing by Paul Thomasch)