The California legislature on Thursday approved a redistricting package aimed at giving Democrats five more seats in the US Congress, countering a partisan advantage President Donald Trump hoped to gain from a similar Republican plan to redraw political maps in Texas.

California Democrats pushed the three bills through the state Senate and Assembly in a remarkable flurry of fast-track action, ahead of a Friday deadline set for getting the newly drawn districts on the ballot in time for a special election on November 4.

Swift passage of the measures marked a decisive victory for Governor Gavin Newsom, who has led the charge in pushing back against what he and fellow Democrats nationally have decried as Trump's attempt at a power grab in the Republican-led state of Texas.

Newsom, who enjoys a Democratic super-majority in both houses of the California legislature, ultimately seeks voter support for his plan. If it succeeds, it would neutralise the Trump-backed Texas bill designed to flip five Democratic seats to Republican control in the US House of Representatives.

Republicans, including Trump, have openly acknowledged that the Texas effort is about boosting their political clout by helping to preserve the party's slim US House majority in the November 2026 midterm races. That election already is shaping up as closely fought.

Democrats have characterised their bid to depart from California's usual independent, bipartisan redistricting process – adopted by voters in 2008 – as a temporary "emergency" strategy to combat what they see as extreme Republican moves to unfairly rig the system.

"The decks are stacked against us, so what we need to do is fight back," California Senator Lena Gonzalez, a joint author of the redistricting plan, said as the state Senate opened floor debate on the bill.

Democrats say more than 70 percent of their newly drawn congressional districts were adopted from maps used by the independent commission in formulating the current boundaries.

Republican Senator Tony Strickland objected, saying, "These maps were drawn behind closed doors."

Within six hours, however, the two houses of the legislature had approved all three measures, voting along party lines to approve each bill in succession and sending it to the other body for its concurrence.

Unlike the California initiative, the newly drawn district lines in Texas would go into effect without voter approval, though Democrats have vowed to challenge the plan in court.

The Texas measure cleared a major hurdle on Wednesday when the state House of Representatives in Austin adopted it on an 88-52 party-line vote.

The Texas Senate is expected to pass the measure next, possibly on Thursday. The two versions of the bill may then need to be reconciled before the legislation goes to Republican Governor Greg Abbott, who has said he will sign it.

"Big WIN for the Great State of Texas," Trump said on his Truth Social platform.

Democrats and civil rights groups say the new Texas map further dilutes the voting power of Hispanic and Black voters, violating federal law that forbids redrawing political lines on the basis of racial or ethnic discrimination. (Reuters)