The Trump administration is prepared to legally challenge California’s long-standing authority to set fuel efficiency standards independent of the federal government, The Associated Press reported Thursday.

California has been at odds with the federal government from nearly the moment President Donald Trump was inaugurated. Arguably the most powerful of the 50 states – with 39 million people and the world’s fifth-largest economy, the Golden State has sued the Trump administration nearly 60 times over issues like immigration, sanctuary cities, and environmental rollbacks.

One of the state’s key victories came in July, when four automakers – Ford, Honda, BMW and Volkswagen – agreed to stricter fuel efficiency standards demanded by California, executing an end-run around the Trump administration’s efforts to relax standards developed during the Obama administration.

The move angered Trump, who lashed out at Ford in a series of tweets.

It’s well established that the auto industry does not favor the 5% boost in fuel efficiency mandated under the Obama administration rule. But automakers do not want to be forced to manufacture two sets of vehicles – one for the most populous U.S. state and another for the rest of the country.

The U.S. Environmental Protection Agency is in the process of preparing a method by which the federal government can establish a single, less rigorous MPG requirement on new vehicles that will be enforceable throughout the country, according to an official who spoke to the AP on the condition of anonymity.

Trump and his acolytes maintain the mileage standards favored by Obama and California are burdensome and will cost consumers significantly more money by raising the price of cars, thereby harming the auto industry – an industry to which the president is finely attuned.

Environmentalists say the mileage standards are necessary to reduce greenhouse gas emissions and will benefit consumers by saving money on gasoline expenditures.

California has a unique relationship to the federal government as it relates to fuel efficiency standards. Due to persistent air quality issues that afflict California, Congress granted the Golden State unique authority to regulate vehicle emissions decades ago under the Clean Air Act.

Any legal challenge to California’s ability to set its own standards will likely run up against this fact, according to experts.

Margo Oge, director of the EPA’s Office of Transportation and Air Quality from 1994 to 2012, told the AP that the Trump administration is likely to lose in a court challenge of California’s powers.

“There is nothing under the Clean Air Act that allows the EPA to revoke a waiver that was given to the state,” she said. “They cannot do that, in my view, based on 20 years managing the program.”

Should the Trump administration move forward with a plan to set a single standard, California Attorney General Xavier Beccera indicated Thursday the state is prepared to duke it out in court.

“California will continue its advance toward a cleaner future. We’re prepared to defend the standards that make that promise a reality,” he said in a statement.

— By Matthew Renda