SACRAMENTO, the United States -- California Governor Gavin Newsom and state officials launched a fierce counterattack on Thursday after the US Senate voted to kill the state's groundbreaking plan to phase out gasoline-powered cars by 2035, promising immediate legal action against an illegal congressional maneuver.

The Republican-controlled Senate voted 51-44 along party lines to revoke federal waivers that allowed California to mandate at least 80 percent of new car sales be electric vehicles by 2035. The measure now heads to President Donald Trump, marking the first time in over six decades that Congress has blocked any of California's vehicle emission standards.

"We won't stand by as Trump Republicans make America smoggy again -- undoing work that goes back to the days of Richard Nixon and Ronald Reagan," Newsom declared in a statement on Thursday. "We're going to fight this unconstitutional attack on California in court."

California Attorney General Rob Bonta immediately announced that the state would file a suit against the Trump administration, calling the congressional action unlawful.

The forceful response reflected California's determination to defend decades of environmental leadership despite what officials characterize as policy mistakes by the Trump administration.

Senator Adam Schiff, a California Democrat, posted on X on Wednesday and accused Senate Republicans of "doing the bidding of the oil industry" after Trump promised to help them if they donated 1 billion US dollars to his campaign.

Legal experts said California had strong grounds for its challenge. Ann Carlson, law professor of the University of California, Los Angeles, told CalMatters that Congress violated its longstanding practices. She called the decision "totally norm-busting."

"We're just in a completely new territory," she said. Congress is "willing to use a statute that doesn't apply, which is highly unusual. We've never seen this before."

Both the Government Accountability Office and the Senate parliamentarian advised that California's waivers cannot be legally repealed using the Congressional Review Act, the mechanism Republicans employed. The parliamentarian serves as the Senate's neutral arbiter of procedural rules.

The Senate's action threatens to unravel a complex web of climate policies spanning multiple states. Eleven states, plus Washington, D.C., have adopted California's electric vehicle mandate, representing more than 30 percent of the US auto market.

California's rules require 35 percent of new light-duty vehicles sold in 2026 to be zero-emission models, rising to 68 percent by 2030.

California Senator Alex Padilla, who grew up in the smoggy San Fernando Valley in Los Angeles, reminded colleagues during a Senate debate that children were regularly sent home from school due to dangerous air quality.

"I wonder if any other member of this chamber grew up like I did," Padilla said during a Senate session ahead of the vote.

The Senate's decision would force California to rely on voluntary efforts and financial incentives rather than mandates to meet federal health standards for smog and particulate matter, the CalMatters reported Thursday. However, the state faced a 12-billion-US-dollar budget deficit that limits its ability to offer substantial rebates.

For nearly 60 years, California has held unique authority under federal law to set stricter vehicle emission standards than national requirements, with other states able to adopt California's rules. The state argued this authority remains essential as federal environmental protections weaken under the Trump administration.