State prosecutors from California to Massachusetts blasted the Trump administration for proposing weaker auto fuel-efficiency standards they said would imperil clean air and increase greenhouse gases.

Months after they pre-emptively sued to block anticipated efforts by the Environmental Protection Agency to roll back mileage regulations, Democratic attorneys general vowed to continue their fight in the courts.

California Attorney General Xavier Becerra also promised another lawsuit if the administration makes good on what he called “arbitrary and capricious” plans to revoke a longstanding waiver allowing California and other states to set their own stricter auto emissions standards. At least 12 other states and the District of Columbia follow California's rules.

Officials in the Trump administration said their actions would make autos more affordable and that would make roads safer because more motorists would be driving newer cars with the latest safety features.

Becerra and attorneys general from 16 other states sued in May to stop the EPA from scrapping standards that would have required vehicles by 2025 to achieve 36 miles per gallon (58 kilometers per gallon) in real-world driving, about 10 miles over the existing standards. The Trump proposal would freeze standards at 2020 levels when vehicles will be required to hit an average of 30 miles per gallon in real-world driving.

States that joined the lawsuit said the change would end up costing more money at the pump because vehicles won't go as far on a gallon of gas, and more misery for those suffering pollution-exacerbated maladies such as asthma.

Other states that joined in the lawsuit with Pennsylvania were: Connecticut, Delaware, Illinois, Iowa, Maine, Maryland, Minnesota, New Jersey, New York, Oregon, Rhode Island, Vermont, Washington, Massachusetts, Virginia and the District of Columbia. All have Democratic attorneys general.

—Associated Press report •