President Donald Trump’s fight with California over vehicle greenhouse gas emissions appears destined to become a long court battle, with California and at least one other state vowing Wednesday to sue to sustain the state’s nearly 50-year-old authority to set its own standards.

One day after his EPA administrator vowed to revoke in “the very near future” a waiver that allows California to set stricter mileage standards than the federal government, Trump made the announcement via a series of tweets.

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“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,” he tweeted Wednesday morning, adding “Automakers should seize this opportunity because without this alternative to California, you will be out of business.”

That revocation is expected to be announced formally Thursday morning at news conference with EPA Administrator Andrew Wheeler and Secretary of Transportation Elaine Chao.

Thirteen states and the District of Columbia have followed California’s lead in setting stricter standards, meaning the California rules cover by some estimates more than 40 percent of America’s population. On Wednesday, Washington Gov. Jay Inslee, a Democrat, vowed that he will also pursue legal action to allow the state to maintain its emissions standards.

That came after California Gov. Gavin Newsom and state Attorney General Xavier Becerra, both Democrats, promised to fight Trump’s decision. Any formal legal action will have to wait until Trump formally makes a move to revoke California’s waiver, however.

Newsom called the fight “the game changer” in the fight over climate change. “This is such a pivotal moment in the history of the climate change debate,” he said.

The fight over California’s emission standards is part of a long-running rebuke by the administration of former President Barack Obama’s efforts to sharply reduce greenhouse gas emissions.

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Trump and the Democratic-led government of the nation’s most populous state have also clashed on other issues as California has embraced progressive policies in contrast to the president’s. Trump lost the state to Democrat Hillary Clinton by a 30 percent margin in 2016.

The Trump administration has argued that lowering the emission standards would allow auto manufacturers to sell their vehicles at a lower price, thus encouraging people to buy new vehicles that would be more fuel-efficient and produce cleaner emissions than older vehicles. They say that California’s decision to set its own standards creates confusion for automakers, and want one standard in order to create more regulatory certainty.

The confusion argument was undermined in July, when four automakers — Ford, Honda, BMW and Volkswagen — entered an agreement with California to set a fuel-efficiency standard of 51 miles per gallon on average for the manufacturers’ range of cars and light-duty trucks by 2026, a slightly looser benchmark than the Obama administration’s goal of reaching about 54.5 miles per gallon by 2025.

Trump, who wants to freeze the fuel economy standards at 37 miles a gallon, struck back, threatening to launch an antitrust investigation against the four automakers and threatening California with legal action if it did not back away from the agreement.

‘Partisan assault’

The move outraged Democrats as well as health and environmental groups who say that the move would undo more than 50 years of precedent, dirty the air and contribute to climate change. Tailpipe emissions are the leading contributor to greenhouse gas emissions in the United States.

House Speaker Nancy Pelosi, D-Calif., in a statement late Tuesday said Trump and the EPA “have no authority” to revoke the waiver, and called the move “an outrageous, partisan assault.”

Separately, Sen. Dianne Feinstein, D-Calif., joined two other Senate Democrats to ask the Department of Justice to turn over materials explaining its decision to pursue an antitrust investigation against four automakers.

In their letter to Attorney General William Barr, Feinstein, Sen. Thomas R. Carper, D-Del., and Sen. Maria Cantwell, D-Wash., wrote that the investigation “appears to be nothing more than a politically motivated act of intimidation to discourage additional automakers from joining the agreement.”

Carper, the ranking Democrat on the Senate Environment and Public Works Committee, said the move “flies in the face” of California’s longstanding legal authority to set its own clean car standards. He predicted the move would provoke “years” of litigation and said he was urging other automobile companies to join the four automakers who had entered into the California agreement.

He said it was unlikely Congress would fight the move through the Congressional Review Act because Senate Majority Leader Mitch McConnell would “make sure it would be defeated.”

“I’m confident that when the courts get ahold of this they will strike it down,” he said.

Presidential candidate Sen. Kamala Harris, D-Calif., said she would re-introduce a 2018 Senate resolution asserting the state’s authority to set its own standards, saying Trump’s decision was not based “in scientific fact.”

“The current administration has put a target on California’s back and sought only to score political points by attacking our state.”

House Minority Leader Kevin McCarthy, R-Calif., one of seven Republicans in the state’s 53-member House delegation, said he agreed that it does not make sense to have separate California and federal standards for tailpipe emissions.

He was sharply critical of Newsom for not working with Trump, saying, “I think he should’ve focused and sat down with the president to have a standard for all of America.”

“It seems as though California is just wanting to say no to anything the federal government wants to do instead of sitting down and finding common ground,” he said.