California and 11 other states were awaiting permission for the ambitious measure, which Biden is set to give in one of his final acts during the lame-duck period, two people briefed on the matter told the New York Times. President-elect Donald Trump has repeatedly signaled his opposition to the measure, setting up a legal battle for the second administration.

One-quarter of vehicles bought in California are electric, the highest in any state, yet still far behind the aimed-for 100% in a decade. Trump has vowed to terminate the mandate to fully transition to electric cars.

“California has imposed the most ridiculous car regulations anywhere in the world, with mandates to move to all-electric cars,” Trump said. “I will terminate that.”

The New York Times reported that Trump is expected to revoke Biden’s permission on the first days of his presidency. The matter will likely then go to the courts.

Gov. Gavin Newsom (D-CA) has been trying to move forward with the ban for the last four years. He signed an executive order in 2020 and the California Air Resources Board voted on the regulation two years later.

Initially, the rules were set to let California start phasing out gasoline-powered cars beginning as early as 2026, when the state could require 35% of new cars sold be zero-emission vehicles. The percentage required would ramp up to 68% in 2030 before completely phasing them out by 2035.

“It’s ambitious, it’s innovative, it’s the action we must take if we’re serious about leaving this planet better off for future generations,” Newsom said in 2022. “California will continue to lead the revolution towards our zero-emission transportation future.”  

California has consistently ranked as the state with the most polluted air in the country. Since 1970, it has been allowed to try and improve its air quality by enacting stricter rules and regulations regarding clean air standards than what the federal government says is required.

Other states occasionally followed California’s lead on air quality standards, creating a patchwork system of rules that could lead to legal fights.

Then-Gov. Ralph Northam promised Virginia would mimic California’s move to phase out the sale of new gas-powered cars. However, when Gov. Glenn Youngkin (R-VA) and Republicans won control of the state, he reversed the move.

California is no stranger to legal battles with Trump, having sued the first Trump administration more than 100 times.

Newsom has touted climate measures pushed by him and the Democratic-controlled legislature as major accomplishments.

“California has long led the nation in pioneering climate policies and innovation,” he said earlier this year. “Those efforts will continue for years to come.”