The Environmental Protection Agency and the Department of Transportation are expected to propose a rule within weeks that would require automakers to sell passenger cars that average about 51 miles per gallon of gasoline by 2026.
As other sources of greenhouse gases have declined, transportation has become the largest single source of climate-warming pollution in the United States, accounting for 28% of carbon emissions.
Since the exhaust emission rules are based on the average mileage per gallon of all vehicles sold by a car manufacturer, the stricter standards are intended to force car manufacturers to sell more electric cars to offset sales of conventional pickups, sport-utility vehicles and other low-mileage models. The Ford F-150, for example, is the most popular vehicle in the country and gets only about 20 miles per gallon.
The risk for automakers lies in whether or not consumers will buy electric vehicles. This tends to be logistically difficult because of the high price of electric vehicles and the lack of a network of charging stations for electric vehicles in the country.
According to analysts and people familiar with the government's plans, the shape of future strict rules is likely to depend on the draft Infrastructure Bill.
If Congress approves hundreds of billions of dollars to build charging stations and provide tax incentives for buyers and manufacturers of electric cars and trucks, Mr. Biden will likely gain industry support for stricter rules that will put more electric vehicles on the road. Currently, only about 2 percent of vehicles sold in the United States are electric.