President Obama  nominated Robert Califf, a prominent cardiologist and longtime researcher at Duke University, as the next commissioner of the Food and Drug Administration on Tuesday.

The nomination comes after the resignation this spring of Margaret A. Hamburg, who left the agency in March after a six-year tenure marked by a wave of new drug approvals, as well as legislation to overhaul the nation's food safety system and begin regulating tobacco products for the first time. Stephen Ostroff, previously the FDA's chief scientist, has served as acting commissioner in recent months.

Califf, who has long been considered a likely candidate for the top FDA job, joined the agency as a deputy commissioner in February after several decades as a researcher and administrator at Duke. He has led scores of pivotal clinical trials, been among the nation's most cited medical authors and for years served on various FDA advisory committees.

If confirmed by the Senate -- a considerable if, given the many Obama nominations that have languished in recent years --  Califf would inherit an agency facing broad new responsibilities and potentially on the brink of major changes. The FDA is in the middle of implementing the extensive food safety legislation passed by Congress in late 2010, an effort that has taken years. Likewise, federal regulators are still wrangling with how best to regulate cigarettes and other other tobacco-related products, such as cigars and e-cigarettes.

In addition, new legislation known as the 21st Century Cures Act, which has been working its way through Congress during the past year, could alter the speed and manner in which the FDA approves drugs and medical devices. Advocates have said the bill would help accelerate the agency's reviews and get needed innovations to patients more quickly, though some experts worry the legislation could force the FDA to compromise its high standards for safety and efficacy in the name of speed.

Some health groups were quick to welcome Califf's nomination Tuesday, saying his background as a respected researcher and clinician makes him a strong candidate for the post.

"[He] has been a leader on so many vital issues that directly impact patient's lives. He will bring a truly important and unique perspective," Ellen Sigal, chair of the non-profit Friends of Cancer Research, said in a statement. "This is a very important choice at this time to carry out the mission of an agency that keeps the country safe and gets new therapies to those that need them most."

At the same time, Califf has faced questions about his close ties to the pharmaceutical industry over the years. A 2014 financial disclosure showed his salary at Duke was underwritten partly by funding from large drug makers such as Eli Lilly, Novartis and Merck. He also reported receiving fees from a range of other pharmaceutical companies.

Through an FDA spokesman, Califf declined an interview request Tuesday. But in an interview with Time earlier this year, he said collaborations between academic researchers, the government and the pharmaceutical industry are a necessary, if sometimes uncomfortable, reality of modern drug development.

“The greatest progress almost certainly will be made by breaking out of insular knowledge bases and collaborating across the different sectors,” he told Time, adding that there is "a tension which cannot be avoided between regulating an industry and creating the conditions where the industry can thrive, and the FDA’s got to do both.”

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