Republicans have moved to tighten their grip on power in Texas after a late-night vote in the state’s legislature approved an early sign-off to new congressional boundaries at the expense of communities of color.

The Republican-led effort will give the party powers over redrawn US House maps and shore up its eroding dominance in Texas, whose demographics are becoming less white in a shift that most experts see as favoring Democrats.

The redrawn congressional districts would make make it easier for many Republican incumbents to hold their seats, but critics say they also threaten Black and Hispanic communities’ political influence.

The district map contained in Senate Bill 6 is expected to strengthen Republican numbers in the state’s delegation to Washington from the current 23-13 split in favor of Republicans to a 24-14 or 25-13 advantage, according to the Austin American-Statesman.

Republicans say the districts, which were drawn by the Texas state senate, adhered to federal voting rights law.

Texas Democrats objected to the proposed districts, arguing that Republicans had failed to respect or reflect the sharp increase in Latino, Black and Asian populations who make up more than half of the nearly 4m new Texans over the past decade. The increase gave Texas two seats in Congress last year.

“This map is a bad map,” said Democratic representative Chris Turner of Grand Prairie, a city in Dallas County. “It’s a map that does not reflect that the tremendous growth of our state is 95% attributable to Texans of color. It gives the two new districts that Texas received to Anglos.”

Another Dallas-area democrat, Rafael Anchía, said that SB 6 would increase Anglo-majority districts from 22 to 23, while districts where Hispanics make up the majority of voters would be reduced from 8 to 7. The state’s sole majority-Black district would disappear.

“That doesn’t work morally, it doesn’t work mathematically, and it shouldn’t work in redistricting,” Anchía told the Austin American-Statesman newspaper.

But Houston senator Joan Huffman, the Republican author of SB 6, has said that she created a redistricting plan “blind to race” that meets the requirements of the Voting Rights Act.

The redistricting maps still face final negotiations between the Texas upper and lower chambers before being sent to Governor Greg Abbott, a Republican, who is expected to sign them.

The measures are expected to trigger court challenges by Democrats and voting rights advocates in what could be another high-profile, high-stakes legal battle that has already made Texas the center of abortion rights and immigration battles.

Republicans, who control both chambers, have nearly complete control of map-making process, and are working off maps that the courts have already declared as tilted, or gerrymandered, in their favor.

Representative Van Taylor, for example, whose district in Dallas’ exurbs went for Donald Trump by a single percentage point last year. Under the new maps, reports the Associated Press, Trump would have won the district by double-digits.

Michael McCaul, representative of Texas’ 10th Congressional District, stretching from Austin to Houston could now represent a solidly pro-Trump district, after Houston’s exurbs were peeled away.

Furthermore, the district stretching from the Rio Grande Valley to San Antonio that President Joe Biden won by just over 2% would now slightly tilt toward Trump voters.

But some incumbent Democrats, too, came away with advantages by changing the configuration that placed two Democratic African-American representatives, Sheila Jackson Lee and US Representative Al Green, in the same Harris county district. Another Democratic amendment returned Fort Bliss to the district based in nearby El Paso.