In the final days of the Biden administration, the Food and Drug Administration is seeking White House approval to propose a drastic reduction in the amount of nicotine in cigarettes, a longstanding goal of public health experts that has faced stiff opposition from the powerful tobacco lobby.

The F.D.A. submitted the proposal to the Office of Management and Budget only on Tuesday, a sign that the move was perhaps more wishful and symbolic than realistic for a White House juggling many late-term agenda items. And traditionally, the budget office’s review of agency proposals can take months.

“I think it’s a milestone in progress toward the single most game-changing tobacco regulatory policy, in terms of lives that could be saved, that F.D.A. could ever do,” said Mitch Zeller, a former director of the agency’s tobacco center. “Having said that, it’s only a proposed rule, and we’re obviously in the waning days and weeks of an outgoing administration.”

Even if the F.D.A. receives clearance from the White House to advance the proposal, whether it can survive once President-elect Donald Trump takes office in January is unclear given the sustained opposition from the industry. The tobacco lobby was also a significant donor to Mr. Trump’s campaign; the cigarette maker Reynolds American had given $8.5 million to his main super PAC by late October.

Mr. Trump is known to personally oppose cigarette smoking, but has not weighed in recently on agency issues like nicotine levels in cigarettes. He has chosen Robert F. Kennedy Jr. as his likely nominee to run the nation’s top health agency, and Mr. Kennedy has railed against federal subsidies given to tobacco growers, saying they eclipse those sent to other farmers who grow fruits and vegetables. He listed the problem as evidence that “we are just poisoning” people and contributing to chronic disease.

“It makes no sense if we want a healthy country,” he said in a speech in August.

A World Health Organization study estimated in 2023 that the U.S. Agriculture Department allocated $437 million in subsidies to tobacco farmers from 2015 through 2020.

Dr. Robert Califf, the F.D.A.’s commissioner, first announced the agency’s intent to require tobacco companies to significantly reduce the amount of nicotine in traditional cigarettes in June 2022. The agency’s aim was to slash the addictive nicotine to a level that would make cigarettes undesirable, helping people to quit smoking and cutting the rate of smoking beyond its current, historic low.

The F.D.A. confirmed Wednesday that its proposed rule had reached the White House. An agency spokesman said that if it were finalized, it “would be among the most impactful population-level actions in the history of U.S. tobacco-product regulation.”

Cigarette smoking is linked to about 480,000 premature deaths a year.

To Dr. Califf, who spent decades working as a cardiologist, reducing smoking death and disease has been a central goal in improving the health of the nation. But he has aired frustration about getting proposals to the finish line.

This year, the Biden administration abandoned years of work on a proposal to ban menthol cigarettes, which make smoking more appealing to many people. It was fiercely opposed by Reynolds American, which makes billions of dollars in revenue from its Newport menthol cigarettes. Opponents of the plan framed concerns by Black people who smoke menthol cigarettes as an issue that could potentially cost Mr. Biden votes.

The draft proposal to reduce nicotine levels elicited more than 7,700 comments from the public, including industry. The agency has since refined the plan, although it remains unclear whether the proposal would also affect nicotine levels in cigars, hookahs or e-cigarettes.

If the plan advanced, it would be a landmark change, said Erika Sward, the assistant vice president of national advocacy at the American Lung Association.

“We know that candy flavors and the marketing that tobacco companies do are what attracts kids and young adults to try tobacco products,” she said. “But it’s the nicotine that attracts them and addicts them in this lifelong battle with attempts to quit and with tobacco-caused disease.”

Major cigarette companies including Reynolds American and Altria have responded to the proposal by saying they prefer harm-reduction efforts that include helping smokers make the transition to e-cigarettes, which are believed to be less harmful.

Both companies have previously warned that making cigarettes unappealing to adult smokers would, in effect, be a product ban in violation of tobacco control laws.

“Both an express and a de facto ban would have precisely the same effect — both would eviscerate Congress’s expressly stated purpose ‘to permit the sale of tobacco products to adults,’” according to a letter in 2018 from Reynolds to the F.D.A. about an earlier proposal.