President Donald Trump will revoke California’s ability to regulate car emissions and end the state’s mandate for electric car sales, according to a Bloomberg report Monday.

The proposal will take apart one of former President Barack Obama’s signature regulatory measures designed to curb greenhouse gas emissions, the report notes. Trump’s move to remove California’s ability to set its own standards will likely result in a protracted lawsuit battle.

It will cap federal fuel economy requirements at 2020 levels, which under current law requires at least a 35-mile-per-gallon average. Obama initially placed the level at roughly 50 mpg by 2025, sources told Bloomberg. The measure revokes a section in the Clean Air Act allowing California to sell a higher number of electric vehicles.

Activists criticized the move, calling the reversal an outrageous attack on the state’s ability to set rules governing public health.

“This is nothing less than an outrageous attack on public health and states’ rights,” Frank O’Donnell, president of Clean Air Watch, said Monday in a press statement. “It’s a dumb move for an administration that claims it wants peace, because this will lead to an emissions war: progressive states versus a reactionary federal government. The big question: who will the car companies back?”

California announced a lawsuit in May against the Trump administration after former EPA Administrator Scott Pruitt promised in April to review a set of Obama-era efficiency rules the auto industry considers too burdensome.

Obama aimed to raise the average fuel economy of automobiles to more than 50 miles per gallon within 10 years. The Golden State got permissions from the Obama administration to issue its own, higher emissions standards. They require cars get 54.5 miles per gallon by 2025. The rules would cut 540 million metric tons of carbon dioxide emissions and save consumers money, officials estimated.

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This article originally appeared in The Daily Caller