A letter from the governors of 12 states calls on U.S. President Joe Biden to back the phase-out of internal combustion engine vehicles by 2035. The letter follows calls from two California Senators to set an end date for new ICE-powered vehicles.

In the letter, seen by Reuters, the governors from states such as Connecticut, Hawaii, New Jersey, New Mexico, California, and more, asked Biden to “ensure that all new passenger cars and light-duty trucks sold are zero-emission no later than 2035.” The letter also calls for milestones to be set and for a way to monitor progress to be established.

The governors argue that “by establishing a clear regulatory path to ensuring that all vehicles sold in the United States are zero-emission, we can finally clear the air and create high-road jobs.”

Read More: Biden Urged To Set End Date For ICE-Powered Vehicle Sale By Two California Senators

United Auto Workers president Rory Gamble expressed some discomfort at the letter, though, noting that EVs require fewer workers than ICE-powered vehicles. According to Reuters, he asked that the government ensure that the transition to EVs is “stable, reliable and creates quality union jobs.”

President Biden has encouraged the adoption of electric vehicles, requiring the entire government fleet to be transitioned to electric and encouraging the production of batteries in the U.S. The governors, though, want tougher fuel-economy standards to be set and more incentives to be aimed at encouraging EV adoption.

Indeed, many automakers are promising that they will go all-electric, or at least electrified, by 2035. The governors added that they also want penalties against companies that overshoot fuel economy standards to be brought back to pre-Trump administration levels in order to help fund charging infrastructure.

California and Michigan have already vowed to ban the sale of internal combustion engine vehicles by 2035. Biden said in October that he did not support the plan.