Setting up a showdown with California, the Trump administration on Thursday announced a plan to revoke a signature Obama-era environmental regulation.
The administration wants to freeze a rule mandating that automakers work to make cars substantially more fuel efficient. It called its plan a "50-state fuel economy and tailpipe carbon dioxide emissions standard for passenger cars and light trucks."
The administration also proposed a withdrawal of California's Clean Air Act preemption waiver. California and about a dozen states that follow its rules account for about a third of all the passenger vehicles sold in the United States.
California Governor Jerry Brown called the proposal "reckless."
"For Trump to now destroy a law first enacted at the request of Ronald Reagan five decades ago is a betrayal and an assault on the health of Americans everywhere," said Brown, in a statement. "California will fight this stupidity in every conceivable way possible."
Thirteen states, plus Washington, DC, have adopted California's standards. Colorado announced plans to become the fourteenth.
The attorneys general of 20 states, including California, pledged to sue the administration. They called the plan illegal, saying it would force motorists to pay more for gas and create more air pollution.
The Corporate Average Fuel Economy standards require automakers' cars to average about 50 miles per gallon by 2025. The standards, enacted in 2012, get stricter every year leading up to 2025. The Trump administration's proposal would cut off the average CAFE increases in 2020, when automakers will have to produce cars that get an average of 43.7 miles per gallon.
"It's still a very aggressive program. We have been steadily increasing the standards... for almost a decade," said EPA Assistant Administrator Bill Wehrum on a call with reporters Thursday.
The EPA and Department of Transportation cited safety as one reason for the changes. They claimed the reduced standards would make new cars more affordable. That would allow more people to buy cars with enhanced safety features, the government said. The administration said the proposed plan will prevent thousands of on-road fatalities and injuries.
The public will have 60 days to comment on the plan before any action is taken.
Automakers, represented by the Auto Alliance and Global Automakers, said they support "substantive negotiations" about fuel efficiency standards.