Colorado has become the 11th state to adopt California's zero-emission-vehicle mandate forcing automakers to sell more electric cars in the state.

The new rule was passed by Colorado's air-quality commission by a vote of 8 to 1 on Aug. 23. It requires at least 5% of an automaker's new car lineup to be electric vehicles, or EVs, by 2023 and more than 6% by 2025.

"It's a modest proposal in the face of a critical threat. Where the federal government refuses to act, states must lead," Garry Kaufman, director of Colorado's Air Pollution Control Division, said in a statement.

The Colorado agreement, which echoes the one announced by California regulators, is tougher than the planned rollback of the Corporate Average Fuel Economy, or CAFE, standards the White House previously outlined.

Similar to California's zero-emission vehicle rules, automakers are granted some flexibility by receiving credits for the electric cars they sell before the new mandate is put into place. Companies can also buy credits from other automakers that outperform emissions targets.