President Donald Trump is putting in place fresh leadership at the Food and Drug Administration, announcing plans Friday to nominate a new commissioner and replacing the acting chief to run the agency until a permanent one is approved by Congress.

Trump will nominate Stephen Hahn, an oncologist and chief medical executive at Texas' MD Anderson Cancer Center, to be the next FDA commissioner. Deputy Health and Human Services Secretary Brett Giroir will become acting commissioner in the meantime.

Ned Sharpless has been serving as acting commissioner since Scott Gottlieb stepped down in April after running the agency for nearly two years. Federal rules limit how long officials can work on an acting basis before a president must appoint a new nominee for congressional review.

Sharpless will return to his previous role as director of the National Cancer Institute.

Trump's nominee, if approved, will join the agency at a turbulent time. The FDA faces a teen vaping epidemic and is pursuing policies unpopular with Trump's conservative allies, including removing flavored e-cigarettes from the market.