– Environmental Protection Agency Administrator Scott Pruitt announced Monday that he would revoke Obama-era standards requiring that cars and light trucks sold in the U.S. average more than 50 miles per gallon by 2025, a move that could change the composition of the nation’s auto fleet for years to come.

The push to rewrite the first-ever carbon limits on cars and SUVs, which came out of an agreement among federal officials, automakers and the state of California, is sure to spark a major political and legal battle.

California has authority under the Clean Air Act to set its own emissions limits, and it has threatened to sue if it is blocked from imposing stricter targets. Such a fight has broad implications because 12 other states follow California’s standards.

Pruitt’s decision reflects the power of the auto industry, which asked him to revisit the Obama administration’s “midterm evaluation” review of the model years 2022-2025 fuel-efficiency targets just days after he took office. President Donald Trump told autoworkers in Detroit last year that he was determined to roll back the emissions rules as part of a bigger effort to jump-start the nation’s car industry.

“The Obama administration’s determination was wrong,” Pruitt said in a statement. “Obama’s EPA cut the Midterm Evaluation process short with politically charged expediency, made assumptions about the standards that didn’t comport with reality, and set the standards too high.”

Gloria Bergquist, a vice president at the Alliance of Automobile Manufacturers, said in a statement that her members “support the administration for pursuing a data-driven effort and a single national program as it works to finalize future standards. We appreciate that the Administration is working to find a way to both increase fuel economy standards and keep new vehicles affordable to more Americans.

Pruitt did not specify what limits would be put in place, saying the EPA and the National Highway Traffic Safety Administration would establish a national standard that “allows auto manufacturers to make cars that people both want and can afford — while still expanding environmental and safety benefits of newer cars.”

California officials wasted no time Monday in excoriating the decision.

“This is a politically motivated effort to weaken clean vehicle standards with no documentation, evidence or law to back up that decision,” Mary Nichols, head of the California Air Resources Board, said in a statement. She argued that the move would “demolish” the nation’s shift toward cleaner cars and that “EPA’s action, if implemented, will worsen people’s health with degraded air quality and undermine regulatory certainty for automakers.”