WASHINGTON — The Biden administration on Wednesday will propose the nation’s most ambitious climate regulations to date, two plans designed to ensure two-thirds of new passenger cars and a quarter of new heavy trucks sold in the United States are all-electric by 2032.

If the two rules are enacted as proposed, they would put the world’s largest economy on track to slash its planet-warming emissions at the pace that scientists say is required of all nations in order to avert the most devastating impacts of climate change.

The new rules would require nothing short of a revolution in the U.S. auto industry. Last year, all-electric vehicles were just 5.8 percent of new car sales in the United States and fewer than 2 percent of new heavy trucks sold.

“By proposing the most ambitious pollution standards ever for cars and trucks, we are delivering on the Biden-Harris administration’s promise to protect people and the planet, securing critical reductions in dangerous air and climate pollution and ensuring significant economic benefits like lower fuel and maintenance costs for families,” the Environmental Protection Agency’s administrator, Michael S. Regan, said in a statement.

The E.P.A. cannot mandate that carmakers sell a certain number of electric vehicles. But under the Clean Air Act, the agency can limit the pollution generated by the total number of cars each manufacturer sells. And the agency can set that limit so tightly that the only way manufacturers can comply is to sell a certain percentage of zero emissions vehicles.

The proposed tailpipe pollution limits for cars, first reported by The New York Times on Saturday, are designed to ensure that 67 percent of sales of new light-duty passenger vehicles, from sedans to pickup trucks, will be all-electric by 2032. Additionally, 46 percent of sales of new medium-duty trucks, such as delivery vans, will be all-electric or of some other form of zero-emissions technology by the same year, according to the plan.

The E.P.A. also proposed a companion rule governing heavy-duty vehicles, designed so that half of new buses and 25 percent of new heavy trucks sold would be all-electric by 2032.

Combined, the two rules would eliminate the equivalent of carbon dioxide emissions generated over two years by all sectors of the economy in the United States, the second biggest polluting country on the planet after China.

But some autoworkers and manufacturers fear that the transition to all-electric vehicles envisioned by the Biden administration goes too far, too fast and could result in job losses and lower profits.

Major automakers have for the most part invested heavily in electrification. Nonetheless, several are apprehensive about customer demand for the pricier all-electric models; the supply of batteries; and the speed with which a national network of charging stations can be created.

Autoworkers fear job losses, since electric vehicles require fewer than half the number of workers to assemble than cars with internal combustion engines do.

Automakers and union workers have been expressing those fears directly to the president since 2021, when Mr. Biden announced an executive order directing government policies to ensure that 50 percent of all new passenger vehicle sales be all-electric by 2030.

As word began to spread last week that his new regulations were designed to go still further, some automakers pushed back.

John Bozzella, president of the Alliance for Automotive Innovation, which represents large U.S. and foreign automakers, questioned how the E.P.A. could justify “exceeding the carefully considered and data-driven goal announced by the administration in the executive order.”

“Yes, America’s transition to an electric and low-carbon transportation future is well underway,” Mr. Bozzella said in a statement. “E.V. and battery manufacturing is ramping up across the country because automakers have self-financed billions to expand vehicle electrification. It’s also true that E.P.A.’s proposed emissions plan is aggressive by any measure.”

“Remember this: A lot has to go right for this massive — and unprecedented — change in our automotive market and industrial base to succeed,” Mr. Bozzella said.

Engineers and scientists at the E.P.A. have been working over the past year to determine how much electric vehicle technology is likely to advance in the next decade in order to set the strongest, achievable tailpipe emissions limits.

Tensions between the auto industry and the Biden administration played out over the past week, as the administration was forced to rearrange its rollout of the proposal, according to three people familiar with what happened.

Officials had originally planned for Mr. Regan to announce the policies in Detroit, surrounded by American-made all-electric vehicles.

But as auto executives and the United Auto Workers learned the details of the proposed regulations, some grew uneasy about publicly supporting it, according to the people familiar with their thinking. The setting was moved from Detroit to the E.P.A. headquarters in Washington, where Mr. Regan is scheduled to make remarks Wednesday at 11 a.m.

In an interview, Mr. Regan acknowledged that some auto executives and leaders of the United Auto Workers had expressed anxiety over the proposals — adding that they could be amended to assuage those fears.

“We’re very mindful that this is a proposal, and we want to give as much flexibility possible,” he said. The agency will accept public comments on the proposed rules before they are finalized next year. The rules would take effect starting with model year 2027.

Environmentalists praised Mr. Biden for delivering on a promise he made during his first days in office, when he called climate change a “moral imperative, an economic imperative” that would be central to all his decision-making.

A 2021 report by the International Energy Agency found that nations would have to stop sales of new gasoline-powered cars by 2035 to keep average global temperatures from increasing 1.5 degrees Celsius (2.7 degrees Fahrenheit) above preindustrial levels. Beyond that point, scientists say, the effects of catastrophic heat waves, flooding, drought, crop failures and species extinction would become significantly harder for humanity to handle. The planet has already warmed by an average of about 1.1 degrees Celsius.

Mr. Biden has pledged to cut the country’s emissions in half by 2030 and to stop adding carbon dioxide to the atmosphere by 2050. He took a major step toward meeting that target last summer, when he signed the Inflation Reduction Act. It includes $370 billion in spending over the next decade to fight climate change, including tax incentives up to $7,500 for the purchase of American-made electric vehicles.

That law is projected to help the United States cut its emissions by 40 percent by 2030 — not quite enough to meet Mr. Biden’s pledge. Experts said the new E.P.A. regulations, if enacted as proposed, are needed to reach Mr. Biden’s goal.

“The EPA standards are a huge step forward in addressing the largest source of climate pollution: transportation,” said Luke Tonachel, senior director of the clean vehicles and buildings program at the Natural Resources Defense Council, an environmental advocacy group.

A sharp rise in electric vehicles in the United States could mean wider availability and sales of electric vehicles outside its borders, Mr. Tonachel said. “This can be a world-leading standard that puts the world on a much-needed pathway for curbing global pollution from transportation,” he said.

Laurence Tubiana, the CEO of the European Climate Foundation who helped broker the 2015 Paris climate accord, welcomed the E.P.A.’s action.

“This is confirmation to the world of the seriousness of the engagement of Joe Biden on climate change and keeps the U.S. as a front-runner on climate,” Ms. Tubiana said. “It’s resonating very well in Europe and the world.”

Still, others see the proposed regulations as government overreach and say they will surely face legal challenges.

“They are using this established longstanding statute for an entirely new purpose, to force an entirely new goal — the transformation of the industry to electric vehicles,” said Steven G. Bradbury, who served as the chief legal counsel for the Transportation Department during the Trump administration. “This is clearly driven by the president’s directive to achieve these results. I don’t think you can do this. Congress never contemplated the use of statutes in this way.”