Robert F. Kennedy Jr., the health and human services secretary, abruptly canceled a meeting this week of a federal task force that helps determine which preventive health measures must be covered fully by insurance companies, raising concerns about the future of the nonpartisan panel.

The U.S. Preventive Services Task Force had been scheduled to meet Thursday, but its members were informed by email Monday, without explanation, that the meeting would be postponed, according to several participants.

“Moving forward, HHS looks forward to engaging with the task force to promote the health and well-being of the American people,” the notice said.

The agency did not respond to a request for comment.

Created in 1984, the 16-member panel of doctors and other health experts plays a pivotal role in determining whether tens of millions of Americans are eligible for lung cancer screenings, stroke reduction medication and scores of other drugs and preventive services.

Members of the all-volunteer panel are chosen by the health secretary. They meet three times a year in person and also take part remotely in weekly meetings.

The decision to cancel the July meeting follows a Supreme Court ruling last month that upheld the work of the task force — but also affirmed Mr. Kennedy’s authority to disregard its recommendations or to remove members before their terms have expired.

Some health experts said they were concerned that the decision to postpone the meeting foreshadowed the kind of change that recently upended another key federal health panel. Last month, Mr. Kennedy fired 17 members of the advisory committee on immunization to the Centers for Disease Control and Prevention, saying that the move would restore the public’s trust in vaccines.

“This is very worrying, because if past is prologue, it may suggest that they are preparing to eliminate or emasculate the committee,” said Peter Lurie, executive director of the Center for Science in the Public Interest.

Mr. Kennedy subsequently appointed eight new members to the immunization committee, at least half of whom had expressed skepticism about some vaccines. Two weeks ago, the panel rolled back longstanding recommendations for flu vaccines containing an ingredient that the anti-vaccine movement has falsely linked to autism.

The preventive services task force has long had bipartisan support in Congress. Its members, many of them primary care doctors and academics at the nation’s leading institutions, are vetted for conflicts of interest, and their four-year terms are staggered — in part to reduce the influence of any one presidential administration.

But recently, critics on the right have accused the task force of embracing a “woke” ideology and have called on Mr. Kennedy to replace its members. An essay published Wednesday in The American Conservative described the task force as part of the “deep state” and claimed it was “pushing faulty race and gender ideology on doctors.”

Supporters of the task force have rejected such characterizations, noting that its recommendations were shaped by medical science and a rigorous rating system.

The meeting agenda for Thursday was focused on the prevention of cardiovascular disease.

If Mr. Kennedy were to replace the task force’s members, it is not immediately clear what prevention services could be at risk. Even if the task force declines to recommend a drug or program, insurance companies can still decide to cover them.

Dr. Bobby Mukkamala, president of the American Medical Association, said that the task force enjoyed widespread support among doctors in the United States and that any effort to politicize the panel could have lasting effects on public health.

“When something works well and helps inform doctors about how to take care of their patients, to postpone the task force’s work just doesn’t make any sense,” he said. “This flies in the face of what is good for the country’s health.”

AcademyHealth, a nonprofit health and research organization, sent a letter to Congress on Wednesday urging legislators to protect the task force from political interference.

The letter, which was signed by more than 100 health organizations, said that task force recommendations were rooted in data, scientific literature and what it called “radical transparency.”

In an interview, Dr. Aaron Carroll, president of AcademyHealth, noted that the task force had been created during the Reagan administration and that its current members had been appointed by both Republicans and Democrats.

“The task force is a model of what it looks like when science directly informs care,” he said, and added, using the task force’s initials: “Every administration has the ability to change the flavor of the U.S.P.S.T.F. But it has to be done in the correct way.”