In addition to his experience as a pharmaceutical executive, Mr. Azar brings to the job impeccable credentials as a conservative lawyer. A graduate of Yale Law School, he was a clerk for Justice Antonin Scalia on the Supreme Court in the early 1990s and spent two years as a young lawyer working for Kenneth W. Starr, the independent counsel who investigated President Bill Clinton.

If he is confirmed by the Senate, Mr. Azar would be returning to a sprawling agency where he served as general counsel and deputy secretary before spending a decade in the pharmaceutical industry. He resigned from Eli Lilly, which makes Cialis, Humulin and Trulicity among other popular and profitable drugs, in January.

Mr. Leavitt dismissed concerns that Mr. Azar’s work at Eli Lilly would interfere with his ability to seek lower drug prices.

“To solve the problems within the pharmaceutical industry, you have to understand the way the distribution system works,” Mr. Leavitt said. “Alex understands that as well as any person in the country.” If he were to be confirmed, Mr. Leavitt added, “Alex doesn’t work for the drug industry — he works for the president of the United States.”

Kathleen Sebelius, who succeeded Mr. Leavitt as health and human services secretary under Mr. Obama, said Mr. Azar’s knowledge of how the department worked would be a valuable asset if he was confirmed. But she said she had no doubt Mr. Azar would use that expertise to reverse the health care changes that she helped put in place.

“He may be the only secretary in modern history other than Tom Price to be given the job to take away people’s health care,” Ms. Sebelius said. “Alex is a smart guy. He clearly has watched the last year or so. I assume his agreement to come in means that he’s O.K. with enforcing or trying to promote the president’s agenda.”

Mr. Trump’s choice of Mr. Azar continues a pattern in which the president has put former industry officials in charge of regulating their former colleagues. At the Department of Health and Human Services, it would fall to Mr. Azar to follow through on the president’s threats to confront drug prices, many of which are manufactured by Mr. Azar’s former company.