President Trump said Wednesday that he would revoke California’s power to limit carbon pollution from cars and light trucks, sparking a legal battle with the nation’s most populous state.

Trump said on Twitter that the decision to take away California’s long-standing authority to impose stricter air pollution rules would lower the sticker price for new vehicles. His tweets came just minutes before the heads of the Environmental Protection Agency and the Transportation Department indicated that they would announce the move Thursday morning.

“The Trump Administration is revoking California’s Federal Waiver on emissions in order to produce far less expensive cars for the consumer, while at the same time making the cars substantially SAFER,” Trump tweeted on Wednesday while in Los Angeles for a fundraiser. “Many more cars will be produced under the new and uniform standard, meaning significantly more JOBS, JOBS, JOBS! Automakers should seize this opportunity because without this alternative to California, you will be out of business.”

The president’s comments echoed in part the proposal made by administration officials last year, who argued that freezing mileage standards between 2020 and 2026 at about 37 miles per gallon would lower the sticker price of vehicles and spur Americans to replace older cars with newer, safer models.

But the Trump administration’s analysis also acknowledged that easing the Obama-era standards would raise U.S. fuel consumption by about a half-million barrels of oil per day, an increase of 2 to 3 percent, and would lead to an increase in greenhouse gas emissions.

Public health experts and environmental groups have insisted that the White House’s proposal ignores the health benefits from more efficient cars that pollute less and would lead people to spend more money at the gas pump. They said the rollback would allow more carbon dioxide to spew from the nation’s vehicles, undermining any chance of curbing climate pollution in the transportation sector, which has emerged as the nation’s largest source of carbon dioxide emissions.

Over thousands of pages, the administration’s proposal last year argues that the costs of meeting existing federal mileage requirements over the next few years would boost the sticker price of vehicles, prompting people to continue driving older cars and trucks rather than buying newer and safer ones. That would in turn increase the risk of crashes, it said. EPA staffers questioned some of those estimates, though the EPA and the Transportation Department ultimately published the proposal jointly.

Trump’s move sets up a potential clash over California’s ability to set more stringent standards for tailpipe emissions and fuel efficiency, a power the courts have upheld for the past half-century. California is pressing ahead with a plan to raise the average mileage of the U.S. auto fleet to 50 mpg by model year 2026, and 13 other states and the District have pledged to adopt those standards.

At a news conference Wednesday, California Gov. Gavin Newsom (D) and other top officials said they would challenge the move in court. The federal government has never revoked an existing waiver for California, though it declined to sign off on one in 2007. The state challenged that decision, and Obama officials granted the waiver in 2009.

“You can’t get serious about climate change unless you’re serious about vehicle emissions,” Newsom said, adding that Trump was acting out of frustration that California had defended its policies in court. “We are winning. He is losing.”

California’s power to set its own standards dates back to 1967 legislation and has been reaffirmed every time Congress amended the law. Its governor pledged Tuesday to sue the federal government if it revoked the state’s existing waiver.

It is unclear whether the auto industry will endorse Trump’s push to ease tailpipe emissions standards. Four companies — Ford, Honda, Volkswagen and BMW of North America — reached an agreement with the California Air Resources Board in July to produce vehicles that would reach an average of nearly 50 mpg by 2026. The Justice Department has launched an inquiry into whether the carmakers violated antitrust law by entering into a voluntary agreement with California.

“Automakers support year-over-year increases in fuel economy standards that align with marketplace realities, and we support one national program as the best path to preserve good auto jobs, keep new vehicles affordable for more Americans and avoid a marketplace with different standards,” said Dave Schwietert, interim president of the Alliance of Automobile Manufacturers, a major trade group.

The Trump administration’s pressure campaign targeting automakers has begun to pay dividends. Not a single company has joined the framework forged in July, and on Wednesday, California officials said those discussions stalled after the Justice Department started its inquiry.

“Well, we’re in a different world now,” said Mary Nichols, who chairs the California Air Resources Board.

Steven Mufson contributed to this report.