Attorney General Phil Weiser has joined 23 states and several cities, including Denver, in filing a lawsuit against the Trump Administration for its new regulation to relax vehicle emissions standards.

“What is at stake is the rule of law, honoring science, and acting based on data and integrity,” Weiser said on a conference call with California Attorney General Xavier Becerra and Michigan Attorney General Dana Nessel, all Democrats.

The U.S. Environmental Protection Agency’s Safe Affordable Fuel Efficient Vehicles Rule would require 1.5% annual improvements in vehicle fuel economy through 2026, compared to 5% that the Obama Administration proposed. While the EPA calculated that the rule would reduce vehicle costs by $2,340 on average and would balance “safety, economics, technology, fuel conservation, and pollution reduction,” opponents argue that the previous iteration of the rule would have reduced oil consumption by 1.2 billion barrels, saved consumers nearly $100 billion in fuel, and cut greenhouse gas emissions.

“Too many reporters fail to mention one very important point: the Obama era CAFE standards were not attainable by the auto industry,” tweeted EPA Administrator Andrew Wheeler on March 31. “The truth is, the SAFE rule sets realistic standards, will reduce pollution, and save lives!”

However, the EPA’s own website notes that through 2018, all 14 large auto manufacturers met the federal emissions standards, creating record-low carbon dioxide emissions.

“What they want more than anything is they want predictability and they want stability,” said Nessel, referring to the automobile manufacturers headquartered in her state. But when asked if she thought the companies would side with the states in their lawsuit, Nessel added, “frankly, no one who’s affiliated with those companies wants to wake up and see themselves on the wrong end of a mean tweet by President Trump.”