The Trump administration is looking to change a rule that allows California to regulate vehicle emissions for residents and freeze fuel efficiency standards at a fleet average of 35 miles per gallon rather than allowing the standard to rise to 50 miles per gallon by 2025.

New York Post:

The Environmental Protection Agency will ask to revoke a federal Clean Air Act waiver empowering California to set vehicle emissions standards, and the U.S. National Highway Traffic Safety Administration will argue that a 1975 fuel efficiency law prevents the state from regulating greenhouse gas emissions, according to Bloomberg News.

The Clean Air Act is President Barack Obama’s signature environmental policy, and the Trump administration move could set off a chain reaction of litigation, the outlet reported.

The proposal would also freeze federal requirements on fuel economy at a fleet-average 35 miles per gallon by 2020, rather than allowing that figure to climb to 50 mpg by 2025 as it is currently set to do.

Trump’s Office of Management and Budget is reviewing the proposal, a draft of which is expected to be released this week for public review. The plan could be finalized by the end of the year, Bloomberg reported.

Proponents are expected to argue that the rollback will make it cheaper and easier to replace old cars, which will in turn reduce traffic fatalities, Bloomberg reported, citing three people familiar with the plan.

Detractors say the scheme is an infringement on states’ rights and bad for Americans’ health.