Cars head north toward downtown Denver on South Broadway on a smoggy day in a file photo. 

 (AP Photo/David Zalubowski)

Colorado's governor has ordered his state to adopt California's vehicle pollution rules, joining other states in resisting the Trump administration's plans to ease up on emission standards.

Democratic Gov. John Hickenlooper on Tuesday told state regulators to try to have California-style low-emission vehicle standards in place by the end of the year.

The order comes about three months after federal regulators announced they would not implement stricter new emissions rules adopted the Obama administration. Those rules would have started with the 2022 model year.

California has a waiver under federal Clean Air Act allowing it to impose tougher standards than the federal rules, and other states can adopt them. If the Trump administration foregoes the stricter Obama-era rules, California could still impose stricter standards.