FILE PHOTO: Texas Senator, Borris Miles, talks to the crowd and press as democratic lawmakers from Texas hold a press conference after leaving their state to deny Republicans the quorum needed to redraw the state's 38 congressional districts, at the Massachusetts State House in Boston, Massachusetts, U.S. August 6, 2025. REUTERS/Lauren Owens Lambert/File Photo
FILE PHOTO: The Heroes of the Alamo Memorial is seen next to the Texas Capitol, prior to the House coming into session for the fifth time since Democratic lawmakers left the state to deny Republicans the quorum needed to redraw the state's 38 congressional districts, in Austin, Texas, U.S. August 8, 2025. REUTERS/Nuri Vallbona/File Photo

By Joseph Ax

(Reuters) -Texas and California - the two most populous U.S. states - are at the center of an expanding national war over congressional redistricting that could determine whether Republicans or Democrats win control of the U.S. House of Representatives in next year's midterm elections.

At U.S. President Donald Trump's urging, Republican Texas Governor Greg Abbott and the Republican-dominated legislature muscled through a new state congressional map aimed at flipping five Democratic-controlled House seats. California's Democratic governor, Gavin Newsom, and Democratic lawmakers have responded by initiating their own redistricting effort targeting five Republican-held districts there.

Other states, both Republican and Democratic, have either followed suit or threatened to do so. While redistricting must occur every 10 years to incorporate U.S. Census data, redrawing maps in the middle of the decade has historically been exceedingly rare.

Republicans won a narrow House majority in 2024 by a margin of only three seats. The party, which controls more state governments than Democrats, appears poised to pick up several seats through redistricting.

The practice of gerrymandering – drawing district lines to benefit one party over another – has contributed to a decline in the number of competitive House seats. Only about 35 to 45 districts out of 435 are seen as competitive by nonpartisan analysts as of early September.

Here is how the process could unfold in various states.

REPUBLICAN GAINS

TEXAS

Abbott signed a new Republican-backed map into law on August 29, declaring that "Texas is now more red in the United States Congress." More than 50 Democratic lawmakers had left the state in early August, denying the state House of Representatives a quorum and temporarily preventing a vote on the map. Republican leaders signed civil arrest warrants and filed petitions attempting to remove some of the Democrats from office; the missing lawmakers returned after California Democrats announced a retaliatory redistricting effort. Republicans already control 25 of Texas' 38 seats under a Republican-drawn map from 2021.

The NAACP and the Lawyers' Committee for Civil Rights Under Law have sued Texas over the redrawn map, arguing it dilutes the power of Black voters and other minorities.

MISSOURI

Republican Governor Mike Kehoe has called a special session beginning on September 3 to redraw the state's congressional map. Republican lawmakers are expected to carve up Democratic U.S. Representative Emanuel Cleaver’s Kansas City-based seat. Flipping his district would give Republicans control of six of the state’s seven seats.

OHIO

A quirk in state law requires the Republican-dominated legislature to pass a new map for 2026, because the previous one, drawn in 2021, was approved with no Democratic votes. Republicans, who already control 10 of the state’s 15 seats, are likely to target at least two Democrats with a new map.

FLORIDA

Republican Florida House Speaker Daniel Perez has already called for a select committee to work on congressional redistricting. Republican Governor Ron DeSantis has expressed support for a new map, which analysts believe could take aim at two Democratic seats in south Florida. Republicans already control 20 of the state’s 28 seats, after DeSantis pushed through the legislature in 2021 a map that flipped four Democratic seats in 2022.

One possible legal hurdle is a constitutional amendment, approved by voters in 2010, that bars the legislature from drawing districts purely for partisan gain. A majority of justices on the Florida Supreme Court, which upheld the 2021 map, were nominated by DeSantis.

INDIANA

The White House has pressured Indiana Republicans to consider redistricting, though Governor Mike Braun has not yet committed to doing so. Republicans control seven of the state’s nine congressional seats and could easily target at least one Democratic incumbent.

DEMOCRATIC GAINS

CALIFORNIA

Governor Gavin Newsom and Democratic lawmakers have advanced a new congressional map designed to flip five Republican-held seats in direct response to the Texas map. The plan requires approval from the state's voters in a November special election, due to a state constitutional provision that places authority over redistricting with an independent commission.

If the ballot measure passes, the commission would again assume redistricting power following the 2030 U.S. Census. There are no statewide elections in California this year, which could make turnout a wild card. Democrats currently hold 43 of the state's 52 districts.

ILLINOIS

Democratic Governor JB Pritzker has said he is not inclined to pursue mid-decade redistricting, though he has left enough wiggle room to change his mind if more Republican states embark on their own efforts. But Illinois already has a gerrymandered map in place, with Democrats controlling 14 of the state’s 17 seats. Flipping even one Republican seat could prove challenging.

MARYLAND

Democratic Governor Wes Moore has said all options should be on the table, and some Democratic legislators have proposed redistricting in response to Texas and other Republican states. Democrats already control seven of the state’s eight districts, so any new map could at best flip a single seat. Redistricting could also face legal hurdles: the party attempted to install an 8-0 map in 2022, but a state judge struck it down as unconstitutionally gerrymandered.

UTAH

A state judge on August 25 ordered the Republican-led legislature to redraw the state's congressional map, finding that lawmakers improperly repealed a voter-approved ballot measure creating an independent redistricting commission. The current Republican-drawn map splits Salt Lake County, home to most of Utah's Democratic voters, among the state's four districts. A new map could recreate a Salt Lake-based seat, giving Democrats an opportunity to win there.

NEW YORK

Democratic Governor Kathy Hochul has vowed to respond to Texas, but legal constraints likely make that impossible until 2028. Voters would have to approve a constitutional amendment to permit mid-decade redistricting, and under state law such an amendment cannot be put on the ballot before 2027. Democrats hold 19 of the state’s 26 seats after a more aggressive gerrymander in 2022 was blocked by the courts.

(Reporting by Joseph Ax, additional reporting by Andy Sullivan: Editing by Scott Malone, Nia Williams and Tomasz Janowski)