The Environmental Protection Agency (EPA) announced Monday that it would roll back ambitious emissions standards for cars and trucks, setting up a confrontation with environmentalists and with the State of California.

Southern California Public Radio KPCC explains:

The Environmental Protection Agency said it completed a review that will affect vehicles for model years 2022-2025 but it did not provide details on new standards, which it said would be forthcoming. Current regulations from the EPA require the fleet of new vehicles to get 36 miles per gallon in real-world driving by 2025. That’s about 10 mpg over the existing standard. The agency said in its decision that the regulations set under the Obama administration “presents challenges for auto manufacturers due to feasibility and practicability, raises potential concerns related to automobile safety, and results in significant additional costs on consumers, especially low-income consumers.” … Any change is likely to set up a lengthy legal showdown with California, which has the power to set its own pollution and gas mileage standards and doesn’t want them to change. About a dozen other states follow California’s rules, and together they account for more than one-third of the vehicles sold in the U.S. Currently the federal and California standards are the same.

EPA administrator Scott Pruitt suggested that his agency might challenge California’s waiver under the Clean Air Act, which allows it to set its own, even more ambitious, emissions standards. Doing so, according to Capital Public Radio, would require the EPA to show that California had erred in setting its standards — and that the data it had used during the Obama administration were faulty.

“Cooperative federalism doesn’t mean that one state can dictate standards for the rest of the country,” Pruitt reportedly said.

California Attorney General Xavier Becerra is reportedly threatening to sue the Trump administration over the change. If so, it that lawsuit would be one of several dozen the state has filed since Trump took office.

On Monday, the Trump administration fired back for the second time in as many months, suing the state over a law that demands right of first refusal for any federal land sales in California.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. He was named to Forward’s 50 “most influential” Jews in 2017. He is the co-author of How Trump Won: The Inside Story of a Revolution, which is available from Regnery. Follow him on Twitter at @joelpollak.