The Texas legislature's lower chamber passed a contentious new electoral map on Wednesday that aims to help Donald Trump's Republican Party retain its razor-thin US House majority in the 2026 midterm elections.

The vote had been delayed by two weeks after Democratic legislators fled the southern state to halt the aggressive redistricting drive, which carves out five new Republican-friendly districts.

More than 50 Democrats walked out, stalling legislative business and generating national headlines as they sought to draw attention to the rare mid-decade redistricting push.

The rebels returned this week, but not before their protest had set off a national map-drawing war, with Trump pressuring his party's state-level officials to do everything they can to protect the majority in the US House of Representatives.

The stakes are sky-high for Trump, who will be bogged down in investigations into almost every aspect of his second term if Democrats manage to flip the handful of districts nationwide needed to win back the House in next year's midterm elections.

As lawmakers in the Lone Star State debated the map, Democratic representative Chris Turner called it a "clear violation of the Voting Rights Act and the constitution," according to Austin-based news site The Texas Tribune.

Republican leaders of the Texas House sped up the normal legislative process, bringing the new map to a final vote on Wednesday evening.

It passed along party lines 88-52.

After the state House's green light, it moves to the state Senate, where it has passed in a previous session, before heading to Republican Governor Greg Abbott's desk.

Individual states redraw their own congressional districts, usually only once every 10 years, after the US Census.

But "redistricting can be done at any point in time," argued the Texas map's sponsor, Republican Todd Hunter, according to the Tribune.

"The underlying goal of this plan is straightforward: improve Republican political performance."

There is little Democrats in Texas can do to thwart the map change, but it has prompted retaliation in California, and serious discussions in other Democratic-led states alarmed that the Texas manoeuvre could be replicated nationwide.

Republicans are mulling drawing at least 10 new seats and are targeting Ohio, Missouri, New Hampshire, Indiana, South Carolina and Florida.

State lawmakers in Democratic stronghold California -- the largest and richest US state -- introduced three bills on Monday to create a voter referendum this year for a new congressional map that would effectively counteract Texas.

If approved, the referendum would appear on California's November 4 ballot.

"Nothing about this is normal, and so we're not going to act as if anything is normal any longer," Governor Gavin Newsom told reporters Wednesday.

"Yes, we'll fight fire with fire. Yes, we will push back. It's not about whether we play hardball anymore, it's about how we play hardball."

New York Democrats may follow suit, with Governor Kathy Hochul calling the Texas redistricting plan nothing short of a "legal insurrection." (AFP)