The US Supreme Court has cleared the way for Texas to use a new congressional map that could help the Republican effort to shore up their majority in the coming 2026 midterm elections.

Thursday’s unsigned decision comes after Texas filed an emergency request last month to block a lower-court ruling that blocked the new map, which was passed by the state legislature and signed into law by Republican Governor Greg Abbott in August.

In an apparent 6-3 decision, the Supreme Court said in its “preliminary evaluation of this case”, Texas satisfied the conditions for emergency relief and that the lower court “committed at least two serious errors”.

Three liberal justices dissented.

“The District Court improperly inserted itself into an active primary campaign, causing much confusion and upsetting the delicate federal-state balance in elections,” the order reads.

In November, a lower Texas court said evidence indicated the new voting districts were “racially gerrymandered”, and ordered the state to use the congressional lines they had in place before they redistricted earlier this year.

In the US, gerrymandering – the redrawing of electoral boundaries to favour a political party – is only illegal if it is based on race.

Challenges to the mid-decade redistricting came after Democrat lawmakers in Texas fled the state over the summer to stall voting on the new map, helping trigger a race across other states to change their maps too.

California proposed new maps to offset Texas’ gains, which voters approved during a November special election. The US justice department is suing over the state’s redistricting plan.

In November, Indiana became the latest battleground in the nationwide political tug-of-war, and other states – including Utah and North Carolina – have also entered the fray.

The Supreme Court decision marks a win for President Donald Trump. The new map could add up to five Republican seats for the midterm elections as the party fights to keep its narrow majority, and the president had filed a brief asking the top court to rule in favour of Texas.

However, in a lengthy dissent to Thursday’s order, liberal Justice Elena Kagan said it “disserves the millions of Texans whom the District Court found were assigned to their new districts based on their race”.

Three conservative justices on the court, in a brief concuring opinion, rejected the notion that Republicans in Texas redrew the electoral map based on race.

It is “indisputable” that the impetus to adopt the Texas map – and subsequently the newly redrawn map in California – was “partisan advantage pure and simple”, wrote Justice Samuel Alito, joined by justices Neil Gorsuch and Clarence Thomas.

Texas Gov Abbott celebrated the legal victory, praising the high court for restoring the state’s redistricting maps, saying: “We won! Texas is officially—and legally—more red.”

“The new congressional districts better align our representation in Washington D.C. with the values of our state. This is a victory for Texas voters, for common sense, and for the U.S. Constitution,” he said.

Separately, the leader of the Democrats in the statehouse, Gene Wu, said that the court failed Texas voters and American democracy.

“This is what the end of the Voting Rights Act looks like: courts that won’t protect minority communities even when the evidence is staring them in the face.”