The battlefield is narrowing and the timeline is tightening in a congressional redistricting contest among states seeking a partisan advantage ahead of the November midterm elections.

Virginia voters on Tuesday approved a constitutional amendment authorizing a Democratic redistricting plan that could help the party win several additional House seats in this year's elections. Next up could be Florida, where lawmakers are to begin a special session April 28 for a Republican attempt at congressional redistricting.

LIVE RESULTS: Virginia approves redistricting plan in special election

Voting districts typically are redrawn once a decade, after each census. But President Donald Trump triggered an unusual round of mid-decade redistricting last year when he urged Texas Republicans to redraw House districts to give the GOP an edge in the midterm elections. California Democrats reciprocated, and redistricting efforts soon cascaded across states.

So far, Republicans believe they could win up to nine additional seats in states where they have redrawn congressional districts while Democrats think they could gain up to 10 seats elsewhere because of redistricting. But that presumes past voting patterns hold in November. And that's uncertain, especially since the party in power typically loses seats in the midterms and Trump faces negative approval ratings in polls.

Democrats need to gain just a few seats in November to wrest control of the House from Republicans, potentially allowing them to obstruct Trump's agenda.

Next up on redistricting

Florida

Current map: eight Democrats, 20 Republicans

Proposed map: Republican Gov. Ron DeSantis has called a special legislative session to begin April 28 on congressional redistricting. Republicans haven't yet publicly released a specific plan.

Challenges: The state constitution says districts cannot be drawn with intent to favor or disfavor a political party or incumbent.

Where new House districts were approved

New U.S. House districts have been adopted in seven states since last summer. Five took up redistricting voluntarily, one was required to by its state constitution and another did so under court order.

Texas

Current map: 13 Democrats, 25 Republicans

New map: Republican Gov. Greg Abbott signed a revised House map into law last August that could help Republicans win five additional seats.

Challenges: The U.S. Supreme Court in December cleared the way for the new districts to be used in this year's elections. It put on hold a lower-court ruling that blocked the new map because it was "racially gerrymandered."

California

Current map: 43 Democrats, nine Republicans

New map: Voters in November approved revised House districts drawn by the Democratic-led Legislature that could help Democrats win five additional seats.

Challenges: The U.S. Supreme Court in February allowed the new districts to be used in this year's elections. It denied an appeal from Republicans and the Department of Justice, which claimed the districts impermissibly favor Hispanic voters.

Missouri

Current map: two Democrats, six Republicans

New map: Republican Gov. Mike Kehoe signed a revised House map into law last September that could help Republicans win an additional seat.

Challenges: A Cole County judge ruled the new map is in effect as election officials work to determine whether a referendum petition seeking a statewide vote complies with constitutional criteria and contains enough valid petition signatures. The Missouri Supreme Court rejected a lawsuit claiming mid-decade redistricting is illegal. It's scheduled to hear arguments in May on claims the new districts violate compactness requirements and should be placed on hold pending the potential referendum.

North Carolina

Current map: four Democrats, 10 Republicans

New map: The Republican-led General Assembly gave final approval in October to revised districts that could help Republicans win an additional seat.

Challenges: A federal court panel in November denied a request to block the revised districts from being used in the midterm elections.

Ohio

Current map: five Democrats, 10 Republicans

New map: A bipartisan panel composed primarily of Republicans voted in October to approve revised House districts that improve Republicans' chances of winning two additional seats.

Challenges: None. The state constitution required new districts before the 2026 election, because Republicans had approved the prior map without sufficient Democratic support after the last census.

Utah

Current map: no Democrats, four Republicans

New map: A judge in November imposed revised House districts that could help Democrats win a seat. The court ruled that lawmakers had circumvented anti-gerrymandering standards passed by voters when adopting the prior map.

Challenges: A federal court panel and the state Supreme Court, in February, each rejected Republican challenges to the judicial map selection.

Virginia

Current map: six Democrats, five Republicans

New map: Voters approved a constitutional amendment authorizing new U.S. House districts backed by Democrats that could help the party win up to four additional seats.

Challenges: The state Supreme Court allowed the referendum to proceed, but it has yet to rule whether the effort is legal. The court is considering an appeal of a Tazewell County judge's ruling that the amendment is invalid because lawmakers violated their own rules while passing it.

Where redistricting efforts were denied

Governors, lawmakers or partisan officials pushed for congressional redistricting in numerous states. In at least five states, those efforts gained some initial traction but ultimately fell short in either the legislature or court.

Maryland

Current map: seven Democrats, one Republican

Proposed map: The Democratic-led House in February passed a redistricting plan backed by Democratic Gov. Wes Moore that could help Democrats win an additional seat.

Challenges: The legislative session ended in April without the Democratic-led Senate voting on the redistricting plan. The state Senate president said there were concerns it could backfire on Democrats.

New York

Current map: 19 Democrats, seven Republicans

Proposed map: A judge in January ordered a state commission to draw new boundaries for the only congressional district in New York City represented by a Republican, ruling it unconstitutionally dilutes the votes of Black and Hispanic residents.

Challenges: The U.S. Supreme Court in March granted Republicans' request to halt the judge's order, leaving the existing district lines in place for the 2026 election.

Indiana

Current map: two Democrats, seven Republicans

Proposed map: The Republican-led House passed a redistricting plan in December that would have improved Republicans' chances of winning two additional seats.

Challenges: Despite pressure from Trump to adopt the new map, the Republican-led Senate rejected it in a bipartisan vote on Dec. 11.

Kansas

Current map: one Democrat, three Republicans

Proposed map: Some Republican lawmakers mounted an attempt to take up congressional redistricting.

Challenges: Lawmakers dropped a petition drive for a special session on congressional redistricting in November, after failing to gain enough support.

Illinois

Current map: 14 Democrats, three Republicans

Proposed map: The Democratic Congressional Campaign Committee in October proposed a new U.S. House map that would improve Democrats' chances of winning an additional seat.

Challenges: The Democratic-led General Assembly declined to take up redistricting, citing concerns about the effect on representation for Black residents.