One of the Obama administration’s biggest greenhouse gas emission reduction policies is about to be rolled back… and Austin Mayor Steve Adler is not too happy about it.

Last week, EPA Administrator Scott Pruitt announced that he intends to roll back vehicle emission standards and is starting a process to develop new ones. He also signaled a desire to change California’s unique right (under a waiver from the Clean Air Act) to pass stricter vehicle emission standards than the rest of the country.

“Cooperative federalism doesn’t mean that one state can dictate standards for the rest of the country…It is in America’s best interest to have a national standard, and we look forward to partnering with all states, including California, as we work to finalize that standard,” Pruitt said in a press release. 

In response, Austin Mayor Steve Adler joined together with hundreds of other Climate Mayors (a bipartisan network of 402 mayors committed to demonstrating leadership on climate change) in denouncing the EPA’s decision.

“The standards adopted by the US EPA in 2011 are saving American drivers money at the gas pump, keeping the country competitive in a sector trending toward zero emissions innovation, and cleaning up the air we all breathe,” said the mayors in a press release.“We will continue our efforts to hasten the transition to more efficient and zero emissions vehicles. We had long viewed the federal government as a partner on clean cars, but we won’t let it take us backwards.”

In case you’re not familiar, the Obama Administration rules dictated that all cars in the US would get 54.5miles per gallon by 2025. If fully implemented, the standards were expected to cut carbon emissions by six billion tons, which is roughly equivalent to US greenhouse gas emissions for an entire year.

The EPA decision is expected to be challenged in court.