(CNN) — A federal court on Tuesday tossed out a newly drawn congressional map that created a second majority-Black district in Louisiana – in a potential blow to Democrats seeking to seize control of the US House in November’s elections.

The map, which slashed diagonally through the middle of the state to create the new 6th Congressional District, amounts to an unconstitutional racial gerrymander and cannot be used in any election, US District Judges David Joseph and Robert Summerhays wrote in their majority opinion.

The judges, both nominees of former President Donald Trump, were part of a three-judge panel that presided over an April trial challenging the map. The third judge, Carl Stewart of the 5th US Circuit Court of Appeals and a nominee of former President Bill Clinton, dissented.

The judges set a May 6 hearing for all parties to discuss next steps.

An appeal to the US Supreme Court is likely – casting doubt over what map will be used in this year’s elections. State officials have said they need to know the contours of the district by May 15 to prepare for fall elections. Officials with a Democratic redistricting group led by former US Attorney General Eric Holder said they expect an application for an emergency stay to be filed with the high court, urging the justices to keep the map in place.

In a statement on social media, Louisiana’s Republican Attorney General Liz Murrill said her team was still reviewing the ruling but indicated the state would ask the high court to weigh in.

“I’ve said all along the Supreme Court needs to clear this up,” she wrote.

Louisiana is among the states that saw protracted legal battles over redistricting following the 2020 census. The creation of new districts with sizable Black populations in Louisiana and in Alabama were cast as significant wins for voting rights activists that also could shape the balance of power in the House – where Republicans hold a threadbare majority.

The intense legal skirmishes over redistricting have largely concluded, with observers on both sides of the aisle saying that control of the House could come down to just a handful of seats.

Earlier this year, Louisiana’s GOP-controlled Legislature – with the support of newly elected Republican Gov. Jeff Landry – approved a map with the new district to comply with a federal court order that found the state likely in violation of the federal Voting Rights Act by diminishing the voting power of Black Louisianians. Although Black residents make up roughly a third of Louisiana’s population, the state has just one Black lawmaker – who is also the lone Democrat – in its six-member US House delegation.

The new district lines endangered the reelection chances for the current 6th District officeholder, Republican Rep. Garret Graves, who had backed a Landry rival in the 2023 race for governor.

Supporters of the Legislature’s map argued that political factors, rather than race alone, had shaped its contours.

Graves had predicted the map would not stand. A dozen non-Black voters filed a legal challenge to the district lines, arguing that it violated the US Constitution’s equal protection clause.

The majority on the court agreed.

The evidence at trial, including demographic data, demonstrates that “race was the predominate factor driving decisions made by the State in drawing the contours of District 6,” Joseph and Summerhays wrote. “This evidence shows that the unusual shape of the district reflects an effort to incorporate as much of the dispersed Black population as was necessary to create a majority-Black district.”

Holder, who chairs the National Democratic Redistricting Committee, sharply criticized the ruling in a statement Tuesday night, saying it “unnecessarily puts Louisianians’ right to vote in a very precarious position.”

He argued the map approved by state lawmakers should remain in place for the 2024 election.

(Copyright (c) 2024 CNN. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)

Join our Newsletter for the latest news right to your inbox