The Trump administration will soon announce its decision to roll back the rule, which requires new gasoline cars to have an average fuel economy of 36 miles per gallon (15.3 km per liter), reports the Associated Press. The decision to keep these landmark rules through model year 2025 was made a week before the end of former President Barack Obama’s term.

As part of the Obama administration’s efforts to slow the pace of global climate change, the original rules set in 2012 gave the EPA until early 2018 to review the standards set for cars beyond model year 2021, according to AP.

While carmakers are expected to welcome the new administration’s move, AP reports that it could potentially lead to legal challenges from California and other states, which have adopted their own tough emissions standards. “Attacking the California waiver is a recipe for chaos,” Democratic Senator Edward Markey of Massachusetts told AP.

Senator Kamala Harris from California, also a Democrat, slammed the administration’s anticipated move as “counterproductive,” adding it “could absolutely be harmful to the health and well-being of the residents of our state and the people of our nation.”

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Realistically, requirements for the EPA to show justifications for the change and expectations for legal challenges means that it could be years before the current administration can actually change fuel economy standards, according to AP.

Last month, the Alliance of Automobile Manufacturers, a trade group representing automakers wrote to Scott Pruitt, the new EPA chief, to roll back these requirements, which they said would lead to millions of job losses and more expensive cars.