WASHINGTON — Four Republican U.S. senators on Thursday proposed repealing landmark California vehicle emissions rules in a bid to prevent the state from imposing stricter tailpipe requirements than the federal government.

The U.S. Environmental Protection Agency in June sent the Republican-controlled Congress state vehicle emissions rules for potential repeal, saying the waivers granted under the Clean Air Act for California environmental regulations approved under prior Democratic administrations should have been sent to lawmakers under the ​Congressional Review Act. California sued to block the action in federal court, saying it was illegal to send the waivers to the Senate under the Congressional Review Act.

Consideration under the CRA allows repeal by a simple majority vote rather than the 60 votes needed for most legislation.

Senators Cynthia Lummis, Eric Schmitt, Pete Ricketts and Jon Husted said the waivers allowed the California Air Resources Board “to impose its regulatory agenda far beyond California’s borders.”

The Trump administration has mounted a multi-pronged effort to deny California the ability to require cleaner vehicles and ​more electric vehicles. The EPA has also enacted rules making it easier for automakers to sell more ​gasoline-powered cars and trucks, while making it more expensive to buy EVs.

The waivers granted California authority to enact its own emission standards for cars and trucks as well as lawn, garden and power-washing equipment. The rules have prodded companies to produce cleaner electric models to reduce emissions.

California won approval in 2022 under then-President Joe Biden’s EPA for the state’s current ​vehicle rules known as Advanced Clean Cars I or ACC I, which remain in effect and are one of the waivers targeted.

California’s ​rules require automakers to ​sell a rising number ⁠of electric vehicles and meet increasingly stringent limits on tailpipe emissions that are far tougher than federal rules.

The administration of Republican President Donald Trump plans ​to roll back federal fuel-economy rules, while California says fuel savings ​for consumers from ⁠the rules far exceed higher upfront costs of EVs.

Last year, Congress rescinded authority for California to outlaw traditional gasoline-powered vehicles after 2035 after Toyota, General Motors and other automakers lobbied for relief from California’s emissions regulations.

Congress passed legislation in 2025 to stop collecting penalties for not meeting vehicle tailpipe standards, saving automakers hundreds of millions of dollars.

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(Reporting by David Shepardson in WashingtonEditing by Nick Zieminski and Matthew Lewis)