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.

The end of Maryland's legislative session this week marked the demise of Democratic efforts to reshape the state's U.S. House districts. But Virginia voters are deciding Tuesday on a Democratic redistricting plan that could help the party win several additional House seats in this year's election. And Florida lawmakers are to begin a special session April 28 for a Republican attempt at congressional redistricting.

READ MORE: Federal court rejects GOP-led effort to block House map that helps Democrats in Utah

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 nine additional seats in states where they have redrawn congressional districts, while Democrats think they could gain six 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.

Where redistricting remains in play

Officials in more than a dozen states debated or floated redistricting proposals. The immediate focus is on two states — one led by Republicans, the other by Democrats.

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.

Virginia
Current map: six Democrats, five Republicans

Proposed map: A new U.S. House map passed by the Democratic-led General Assembly could help Democrats win up to four additional seats. For the map to take effect, voters would have to approve a constitutional amendment allowing mid-decade redistricting. That amendment is on Tuesday's ballot.

Challenges: The state Supreme Court ruled the referendum can 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 new House districts were approved
New U.S. House districts have been adopted in six states since last summer. Four 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.

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

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.