Just as the Trump administration is attacking California's right to require electric cars to be sold in the state, California may be gaining support elsewhere.

A new bill introduced in Washington state on Monday would add the state to the 10 others that follow or are in the process of adopting California's electric-car mandate.

Last month, Colorado's new governor, Jared Polis, took the first steps toward signing that state onto California's zero-emissions vehicle mandate, which requires that automakers earn credits by selling electric or fuel-cell cars in order to sell other types of cars in the states.

READ THIS: Colorado takes first step toward California electric-vehicle mandate

Another Washington bill would require that all vehicles purchased by the state be electric by 2023, and local public entities by 2025. The bill would put some teeth into a 2007 law that state agencies were found to be ignoring in a report last May.  

Relatively few electric cars other than expensive Teslas are made available for sale in states that don't follow the California mandate. 

California has the unique right among states to set its own vehicle emissions standards under the Clean Air Act, because it set its own standards before the federal government did. The zero-emissions vehicle mandate is part of that California program.

Since President Trump was elected, the EPA, in conjunction with the NTHSA, which has statutory authority over fuel economy but not emissions, has been working to undermine California's legal ability to set its own standards. Under the Obama administration, the EPA and NHTSA coordinated their emissions and fuel economy standards with California, though they did not incorporate the state's electric vehicle mandate.

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California is continuing to follow those fuel-economy and emissions standards, even as the EPA has announced plans to roll them back and has sued the EPA over plans to freeze them. California's moves will affect other states that have signed on to its program, unless they decide to leave it. 

Currently nine states follow California's zero-emissions vehicle program: Connecticut, Maine, Maryland, Massachusetts, New Jersey, New York, Oregon, Rhode Island, and Vermont. Colorado would be the first central-continent state to join the program, and Washington could make the 11th.