President Trump said Friday that he intends to nominate Stephen Hahn, the chief medical officer of MD Anderson Cancer Center in Houston, as the next commissioner of the Food and Drug Administration, a step that resulted in musical chairs involving some of the government’s highest-ranking health jobs.

In a surprise move, acting FDA commissioner Norman “Ned” Sharpless will immediately return to his previous position as the director of the National Cancer Institute. Brett Giroir, assistant secretary for health at the Department of Health and Human Services, will oversee the FDA until Hahn is confirmed, according to HHS Secretary Alex Azar.

It had been assumed that Sharpless would run the FDA until Hahn was confirmed. However, his term as acting agency head expired Friday. It couldn’t be extended because the White House has not yet officially nominated Hahn, who is still undergoing a background check, officials said. When Sharpless returns to the cancer institute, Doug Lowy, acting director of the institute, will resume his work as principal deputy there.

The movement on Hahn’s nomination is occurring at a critical time for the agency, which is at the center of a debate about banning almost all flavors in e-cigarettes — an action intended to stem sharp increases in youth vaping. Trump announced plans for a broad ban in September, but the agency has not yet issued its final policy. Recently, two people familiar with the discussions said the White House is considering excluding menthol and possibly mint from the ban because of concerns about political backlash from vaping supporters.

Hahn, a radiation and medical oncologist, oversees clinical care at MD Anderson, one of the nation’s top cancer centers. Previously, he served as chief operating officer of the hospital during a period of big losses and staff cuts, and has been praised for helping engineer the cancer center’s financial turnaround.

Sen. Lamar Alexander (R-Tenn.), chairman of the Senate Health, Education, Labor and Pensions Committee, said he looked forward to meeting Hahn. He plans to move “as expeditiously as possible” to confirm Hahn and bring “certainty” to the agency, a committee spokesman said.

Sen. Patty Murray (Wash.) the committee’s ranking, said she planned to vet Hahn thoroughly to determine if he is qualified to be FDA commissioner and will press him to quickly impose a comprehensive ban on flavored e-cigarettes.

She added that she was “alarmed” by the appointment of Giroir as interim FDA chief, saying that he has a “track record of letting ideology drive decisions at the expense of women and families.” An aide said the senator was referring to Giroir’s involvement in policy changes that reduce women’s access to health care, in particular reproductive rights.

When asked for a response to Murray’s comment about Giroir, a spokeswoman for HHS pointed to Azar’s statement, which called him “an indispensable leader” for HHS on several public health priorities.

One of the most high-profile issues Giroir has been involved in is federal funding for fetal-tissue research. He was in charge of an HHS “audit” of such research that began a year ago. At a private meeting of scientists last December at the National Institutes of Health, he acknowledged that there currently is no adequate alternative to such tissue for some research. In June, however, Trump decided to end federal funding of such studies for government researchers and to strictly limit funding for academic researchers. Azar and his aides pushed for a less-restrictive position, The Washington Post reported at the time.

Hahn is described by friends and colleagues as an energetic consensus-builder with a disarming, folksy manner. After a stint at the National Cancer Institute, he joined the University of Pennsylvania in 1996, serving as chair of radiation oncology from 2005 to 2014. He then moved to MD Anderson to become division head of radiation oncology. He has conducted an array of clinical trials, including trials of treating prostate cancer with proton therapy and new ways to combine immunotherapy and radiation.

If confirmed, Hahn would head an agency that regulates a broad swath of the U.S. economy, including brand-name and generic drugs, medical devices, much of the nation’s food supply, and tobacco products.

Hahn, who is married and has four adult children, is an exercise enthusiast and avid football fan. He and his wife, friends say, travel frequently to Italy.

Sharpless, an oncologist who also was a contender for the FDA job on a permanent basis, had been acting FDA commissioner since April, when the previous agency head, Scott Gottlieb, stepped down. He had strong support from medical and other groups. On Friday, Azar praised Sharpless for making progress on key issues such as youth use of tobacco and prescription drug costs.

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