Over lunch at his golf club in Jupiter, Fla., on the first Saturday of May, President Trump got an earful from a group of tobacco executives and lobbyists unhappy with the way the Food and Drug Administration was regulating their industry.

Eventually Mr. Trump had heard enough. He interrupted the conversation to call Dr. Marty Makary, the F.D.A. commissioner.

No answer.

Furious, the president then dialed Dr. Makary’s boss, Health Secretary Robert F. Kennedy Jr., and another top health official, Dr. Mehmet Oz, the head of the Centers for Medicare and Medicaid Services. He complained to them about the F.D.A.’s regulation of e-cigarettes, according to three people briefed on the meeting who were not authorized to discuss it.

The message was received. Less than one week later, the executives got what they wanted.

On Friday, the F.D.A. issued new guidance that could pave the way for major tobacco companies to begin selling flavored vapes and to snare a chunk of the $6 billion e-cigarette market away from illegal Chinese competitors. The new policy bypassed the F.D.A.’s regular rule-making process.

In the intervening week, Dr. Makary continued to argue against approving flavored vapes as support from Mr. Kennedy and others collapsed around him. Health and Human Services Department staff began to draft the new plan, according to two people familiar with the events.

On Tuesday, Dr. Makary resigned, telling associates he could not in good conscience remain the head of an agency that backed such a policy.

Though there is no definitive evidence linking the new guidance to donations or lobbying, the episode represented a clear pivot in the federal government’s longtime approach to the tobacco industry.

Since the 1990s, when states extracted vast payments and other concessions from the major cigarette companies in a nationwide legal settlement, Big Tobacco has been in retreat. Cigarette sales have plummeted, and regulations have mounted as consumers and administrations from both parties embraced public health consensus about the dangers of smoking and nicotine addiction.

Mr. Trump’s first administration initially continued the trend, proposing further restrictions on cigarettes and moving to outlaw flavored vapes over concerns that their rising popularity threatened the health of a generation of adolescents.

But since then, Mr. Trump has enthusiastically welcomed the financial support of the tobacco industry and has courted e-cigarette users as a political constituency.

The new vaping guidance highlights Mr. Trump’s willingness to use his executive authority to prioritize the causes of major corporate donors over public health concerns, taxpayer interests and the judgment of experts, sometimes including those in his own administration.

The president has developed a close relationship with tobacco companies including Altria and Reynolds American, which have donated millions of dollars to his political groups and projects, including his proposed White House ballroom. Their executives attended the lunch at the president’s golf club.

The Department of Health and Human Services, which oversees the F.D.A., referred requests for comment to the White House.

Kush Desai, a White House spokesman, said in a statement that Mr. Trump has pushed to expand access to vapes to help Americans trying to quit smoking.

“The only guiding factor behind the Trump administration’s health policymaking is gold standard science,” Mr. Desai said.

Reynolds American and Altria did not respond to questions about their lobbying or the conversation at the lunch.

It was attended by Jeff Raborn, a top executive at Reynolds, and Phil Park and Todd Walker of Altria, according to the people familiar with the meeting. Also attending were Brian Ballard and Rich Haselwood, lobbyists for the firm Ballard Partners, which represents Reynolds and helped marshal a sophisticated and expensive influence campaign that culminated in the new vaping guidance. Mr. Ballard is a top fund-raiser for Mr. Trump. Mr. Haselwood had been an in-house lobbyist at Reynolds before joining Ballard Partners this year.

A spokesman for Ballard Partners declined to comment.

While public health experts consider e-cigarettes a less harmful alternative to tobacco-burning cigarettes, the new guidance circumvents a scientific review process the F.D.A. had previously defended up to the Supreme Court. The disregarded procedures were meant to ensure approval of only those products shown in studies to help cigarette smokers transition to vapes without attracting a new generation of nicotine users.

The guidance also could allow higher nicotine levels in nicotine pouches. It includes a pledge to prioritize efforts to stop the import of illegal foreign vapes, an idea that has bipartisan support in Congress.

Taken together, the policy changes could help companies like Altria and Reynolds gain market share considered central to the survival of the industry.

The market for vapes and nicotine pouches, like Zyn, is about 30 million people in the United States, on par with the number of cigarette smokers. While the nicotine pouch market is rapidly growing, cigarettes still account for about $50.8 billion, or nearly 70 percent of the annual tobacco sales in the United States, according to a Goldman Sachs research report. Vape sales have lagged amid competition from illicit products.

In recent years, the F.D.A. has moved glacially to approve e-cigarettes, authorizing only those in tobacco or menthol flavors, including some sold by Reynolds and Altria. Unapproved Chinese vapes have poured into the United States, feeding a thriving illicit market with flavors like peach slush and watermelon ice. Last year, industry executives have said, illicit fruit-flavored vapes made up 60 percent of the e-cigarette market.

When Mr. Trump mounted his bid to return to the White House, some in the tobacco industry went all in, hoping he would loosen regulations on vapes and abandon plans by the Biden administration to ban menthol cigarettes and crack down on other cigarette sales.

Mr. Trump in some ways makes for an unlikely savior for the tobacco industry. He has never smoked, but he pledged during his 2024 campaign to “save vaping again.”

Through a subsidiary, Reynolds, which is the biggest seller of menthol cigarettes, donated $10 million to a super PAC backing Mr. Trump’s campaign, according to campaign finance filings. There is no public record of the subsidiary donating to groups supporting Mr. Biden or the campaign of former Vice President Kamala Harris.

Mr. Ballard, whose firm has been paid more than $4.4 million by Reynolds since the beginning of 2017, arranged for Mr. Trump to have dinner during the campaign with Reynolds executives in New York, according to a person familiar with the interactions. The executives urged Mr. Trump to oppose the menthol cigarette ban and expressed concern about Chinese vapes.

Reynolds executives including Mr. Raborn and Mr. Haselwood were such a presence around the campaign that Mr. Trump took to calling them “my tobacco guys,” according to the person familiar with the interactions and a book coauthored by a New York Times reporter and published last year.

When Mr. Trump won, the rest of the industry jockeyed to show support.

Altria donated $1 million to his inaugural committee; the Vapor Technology Association donated $1.25 million; and a subsidiary of Philip Morris donated $500,000.

On Mr. Trump’s second full day in office, his administration withdrew the proposed ban on menthol cigarettes, an initiative the Biden administration had already mostly abandoned. Mr. Trump’s team also set aside a Biden-era proposal to sharply restrict nicotine in cigarettes, an effort meant to speed the transition away from a product known to be deadly.

In applauding the withdrawal of the menthol ban, Billy Gifford, the chief executive of Altria, told investors on an April 2025 earnings call that “we’re hopeful that that activity and momentum continues.”

The courtship intensified.

Reynolds pitched in another $3 million to a different Trump-backed super PAC, while Altria and Juul each donated $1 million.

And Reynolds and Altria each donated to the effort to raise private funds to build a new White House ballroom. Mr. Raborn of Reynolds and Mr. Walker of Altria were invited to a dinner at the White House in October for donors who gave $2.5 million or more, as was Mr. Ballard.

Tadeu Marroco, the chief executive of British American Tobacco, which owns Reynolds American, predicted to investors earlier this year that the Trump administration would clamp down on illegal vapes, saying “it’s very encouraging, the signs that the new administration is giving to address that.”

The companies’ lobbying strategy also has reached into the states, where they are pushing for so-called “registry laws” — of which there are now more than a dozen including in Florida, Virginia and Pennsylvania. Many of those laws restrict e-cigarette sales to only vapes on a list from the F.D.A.

The guidance released last week said it would create such a list.

Sheryl Gay Stolberg contributed reporting.