Food and Drug Administration Commissioner Scott Gottlieb submitted his resignation on Tuesday and will leave his post within a month.

"I'm fortunate for the opportunity that the president of the United States afforded me to lead this outstanding team, at this time, in this period of wonderful scientific advances," Gottlieb wrote in a resignation letter. He did not explain the reason for his departure.

He wrote later in his resignation letter that the agency was "strong in times of crisis," citing the examples of the government shutdown and the drug shortage in Puerto Rico after it was devastated by Hurricane Maria. The FDA was among the hardest hit agencies within the Department of Health and Human Services during the shutdown.

President Trump tweeted that Gottlieb "has done an absolutely terrific job."



....Scott has helped us to lower drug prices, get a record number of generic drugs approved and onto the market, and so many other things. He and his talents will be greatly missed! — Donald J. Trump (@realDonaldTrump) March 5, 2019

The move by Gottlieb, one of President Trump's most popular appointees, was unexpected. Gottlieb wrote on Twitter in January in response to rumors that he planned to resign that "I want to be very clear — I’m not leaving. We’ve got a lot important policy we’ll advance this year."



I’ve heard from friends contacted by an online pharma news pub that’s preparing a story speculating that I’m leaving #FDA. I want to be very clear - I’m not leaving. We’ve got a lot important policy we’ll advance this year. I look forward to sharing my 2019 strategic roadmap soon pic.twitter.com/0xQuXnSPbo — Scott Gottlieb, M.D. (@SGottliebFDA) January 3, 2019

Multiple reports said Gottlieb, 46, was resigning to spend more time with his family in Connecticut. Gottlieb was in the top role for two years in an agency that oversees the safety of food, drinks, medical devices, and medicines.

“All of us at HHS are proud of the remarkable work Commissioner Gottlieb has done at the FDA," Alex Azar, HHS secretary, said in a statement. "He has been an exemplary public health leader, aggressive advocate for American patients, and passionate promoter of innovation. I will personally miss working with Scott on the important goals we share, and I know that is true for so many other members of the HHS family."

Gottlieb, a physician and investor who served as a scholar at the conservative American Enterprise Institute before joining the administration, advanced initiatives related to drug prices and food safety during his tenure as head of the FDA. He is well-respected by Democrats and Republicans and among leaders in the healthcare industry.

Although Gottlieb generally pursued a regulatory-reducing agenda, he also was in the process of cracking down on youth vaping. In recent days, he had called out Walgreens for selling vaping products to minors, and backed raising the minimum age for buying tobacco products to 21. Under his tenure, the FDA approved record numbers of generic drugs, which are generally less expensive for patients than brand-name drugs.

Gottlieb had previously worked in the FDA under the George W. Bush administration.