(Reuters) - An automotive trade group is in talks with Colorado to try to convince the state not to adopt California’s zero emission vehicle (ZEV) mandate.

FILE PHOTO: A small fleet of electric Chevrolet Bolt vehicles are charged by a sun tracking solar panel car charing system in San Diego, California, U.S. October 22, 2018. REUTERS/Mike Blake/File Photo

In January, Colorado Governor Jared Polis signed an executive order directing the state to adopt California’s ZEV rules, joining nine other U.S. states including Maryland, Massachusetts, New Jersey, New York and Oregon. His order said the formal rules to adopt the program would be proposed by May.

The Alliance of Automobile Manufacturers, a trade group representing General Motors Co, Toyota Motor Corp, Volkswagen AG, Ford Motor Co and others, met with Polis on April 15 in a bid to convince him that voluntary efforts to boost electric vehicles make more sense.

The group said in an April 29 letter seen by Reuters that its members would agree to make all EVs available for sale in Colorado that are on sale in California by January 2020 and commit to additional marketing efforts for EVs.

The auto group also pledged to work with Colorado to allow consumers to take advantage of a $5,000 state purchase incentive at the point of sale by taking on the assignment of the credit at the time of sale.

The automakers said they appreciate Colorado exploring “an alternative program that would help Colorado achieve its goals

sooner.”

In a letter to automakers Monday, Colorado state officials said they see “real opportunity to work together.” The state will proceed an initial hearing this week on the mandate “but we seek to continue discussions about a possible ZEV alternative on a parallel path.”

The California ZEV mandate, first adopted in 1990 and revised on numerous occasions, requires a rising number of electric vehicle or other zero emission vehicles.

Last year, California forecast that about 8 percent of the state’s new vehicle sales in 2025 will be zero emission and plug-in electric hybrids.

In August, the Trump administration proposed freezing fuel efficiency standards at 2020 levels through 2026 and barring California from imposing its own vehicle emission rules or setting requirements for zero emission vehicle sales.

California and 18 other states, including Colorado, have said they will fight the Trump administration’s freeze in court, a legal battle that could leave automakers in regulatory limbo for years.