California's two US senators are urging President Joe Biden to set a firm date to phase out fossil fuel powered passenger vehicles as the White House grapples with how to rewrite vehicle emissions rules slashed under former President Donald Trump, Reuters reported.

In a letter going to Biden on Monday (22 March), Democratic senators Alex Padilla and Dianne Feinstein called on Biden "to follow California's lead and set a date by which all new cars and passenger trucks sold be zero-emission vehicles". They also urged Biden to restore California's authority to set clean car standards.

Reuters noted that, last September, California governor Gavin Newsom signed an executive order directing the state's air resources agency to require all new cars and passenger trucks sold in California to be zero-emission by 2035.

Biden's campaign in 2020 declined to endorse a specific date to end ICE-powered vehicle sales but he has vowed to dramatically boost electric vehicles and charging stations.

In January, Biden said the administration would replace the federal government fleet of 650,000 vehicles "with clean electric vehicles made right here in America made by American workers".

According to Reuters, the senators also said Biden should use a compromise deal that California struck with automakers including Ford, Honda, BMW and Volkswagen that falls between the Trump administration and Obama-era requirements.

"We believe the national baseline should, at an absolute minimum, be built around the technical lead set by companies that voluntarily advanced their agreements with California," Padilla and Feinstein wrote in the letter seen by Reuters. "California and other states need a strong federal partner."

Shortly after taking office, Biden ordered US agencies to revisit fuel efficiency standards by July.

He also directed the Environmental Protection Agency and the National Highway Traffic Safety Administration by April to reconsider Trump's 2019 decision to revoke California's authority to set its own auto tailpipe emissions standards and require rising numbers of zero-emission vehicles.

California vehicle emissions standards are followed by 13 other states and the District of Columbia accounting for more than 40% of the US population, Reuters noted.