SACRAMENTO, United States, Nov. 13 (Xinhua) -- The administration of U.S. President Donald Trump on Thursday moved to block California's new congressional map by suing the state and joining a Republican lawsuit against Proposition 50 (Prop 50), a voter-approved measure that could shift several U.S. House seats in the 2026 mid-term elections, according to federal court filings and official statements.

In a complaint filed in federal court, the U.S. Department of Justice (DOJ) alleged that the map enacted under Prop 50 is a "race-based redistricting plan" that violated the 14th Amendment's Equal Protection Clause and the federal Voting Rights Act, the department said in a press release.

U.S. Attorney General Pamela Bondi described California's approach as a "brazen power grab that tramples on civil rights and mocks the democratic process," said the statement.

The DOJ filing seeks to intervene as a plaintiff in Tangipa v. Newsom, a lawsuit brought on Nov. 5 by the California Republican Party and 19 voters. The suit claims that the Prop 50 map created an unconstitutional racial gerrymander "to favor Hispanic voters," reported Democracy Docket, a voting rights litigation tracker.

The federal government asked judges in the Central District of California to bar the new districts from being used in the 2026 election cycle and to declare that Prop 50 was adopted in a way that abridges voting rights on account of race, according to Democracy Docket's summary of the DOJ motion and complaint.

Prop 50 allows the California legislature to replace the existing U.S. House map -- drawn by an independent citizens' commission -- with a new map for the 2026, 2028 and 2030 elections. After the next national census, the commission would resume control, according to the state's official voter guide and analysis by the University of California, Berkeley's Institute of Governmental Studies.

The measure was designed as a response to mid-decade redistricting efforts in Republican-led states. The constitutional findings stated that Trump had urged Republican officials in Texas to redraw districts in August to "rig the 2026 United States midterm elections," and described Prop 50 as a "temporary" countermeasure, according to the amendment text published by the California legislature.

Governor Gavin Newsom signed the legislative package on Aug. 21, calling it the "Election Rigging Response Act." He said Californians deserved a chance to "fight back" against what he described as Trump's efforts to undermine the democratic process.

The "Yes on 50" campaign, funded by Newsom's ballot-measure committee and supported by the California Democratic Party and major labor and civil rights organizations, urged voters to adopt what it called "temporary, emergency congressional district maps to counter Donald Trump's scheme to rig next year's congressional election," according to the campaign website.

Despite multiple pre-election lawsuits seeking to block the ballot measure or stop the legislature's map, state courts, including the California Supreme Court, allowed the special election to proceed, Democracy Docket reported. On Nov. 4, Californians approved Prop 50 with about 64 percent of voters in favor, based on figures compiled from official returns by Ballotpedia.

Local news outlets said the new map could offset Republican gains from redistricting in states such as Texas. Berkeley's Institute of Governmental Studies estimated that the districts may give Democrats a chance to gain up to five additional U.S. House seats, though final results will depend on future elections.

On Wednesday, the Democratic Congressional Campaign Committee, which helped develop the map, was granted permission by the court to intervene in Tangipa v. Newsom to defend Prop 50. ■