California has asked the Biden administration to OK a proposal for all new vehicles sold to be electric or plug-in hybrids by 2035, according to a letter seen by Reuters.

The California Air Resources Board approved the plan in August. The state now has approached the U.S. Environmental Protection Agency to secure a waiver under the Clean Air Act. The waiver would enable new regulations that establish escalating zero-emission vehicle standards starting in 2026. The goal is to cease the sale of new gasoline-only powered vehicles in California by 2035.

CARB Executive Officer Steven Cliff told Automotive News that zero-emission vehicles would effectively replace emissions generated by conventional vehicles, as motor vehicles and other mobile sources are the primary contributors to pollution in California.

Despite California’s efforts, the Biden administration has repeatedly declined to endorse a specific timeline for phasing out gasoline-only vehicle sales. EPA Spokesperson Tim Carroll told Automotive News that the agency would thoroughly consider California's waiver request through an open public process, as is customary.

An EPA proposal unveiled in April forecasted automakers will need to manufacture 60% electric vehicles by 2030 and 67% by 2032 to fulfill the requirements aimed at reducing vehicle emissions by 2032. EVs still accounted for just 5.8% of total U.S. vehicle sales in 2022.

California's zero-emission regulations are expected to curtail smog-causing pollution from light-duty vehicles by 25% by 2037. The rules stipulate that, by 2026, 35% of new-car sales must be comprised of plug-in hybrid electric vehicles, EVs or hydrogen fuel cell vehicles. That figure will increase to 68% by 2030 and reach 100% by 2035.

A 60-page waiver request submitted by California and viewed by Reuters outlined the projected costs and benefits of the state's zero-emission regulations. It estimates that between 2021 and 2040, the rules will result in a cost of $210.35 billion but yield overall benefits amounting to $301.41 billion.

An increasing number of states, including Rhode Island, Washington, Virginia, Vermont, Oregon, New York and Massachusetts, have adopted California's more stringent EV regulations, surpassing the proposals put forth by the Biden administration.

Under CARB's regulation, automakers could sell up to 20% plug-in hybrid electric vehicles by 2035. However, by that time, those vehicles would need to possess a minimum all-electric range of 50 miles.