DETROIT — Transportation Secretary Sean Duffy said in a rule Friday that Biden-era fuel economy standards for gas-powered cars and trucks are illegal and moved to reverse them, paving the way for a likely reset of rules.

Combined with Senate language in the pending budget bill to eliminate penalties for exceeding standards regulating how far vehicles must travel on a gallon of fuel, automakers moving forward could come under less pressure from regulators to reduce their pollution. Ultimately, the nation’s use of electric vehicles could be slowed.

The moves align with the Trump administration’s ongoing efforts to slash federal support for EVs. President Donald Trump has pledged to end what he has called an EV “mandate,” referring incorrectly to former President Joe Biden’s target for half of all new vehicle sales to be electric by 2030. EVs do not use gasoline or emit planet-warming greenhouse gases.

No federal policy has required auto companies to sell — or car buyers to purchase — EVs, although California and other states have imposed rules requiring that all new passenger vehicles sold in the state to be zero-emission by 2035.

When he was in office, Biden imposed increasingly stringent emissions standards for cars and trucks. He included use of EVs in calculating the rules — an inclusion the Trump administration and the auto industry have argued was illegal and raised the bar too high for automakers to meet.“We are making vehicles more affordable and easier to manufacture in the United States,” Duffy said.