The top candidate to head the Centers for Disease Control and Prevention is a longtime AIDS researcher who is well-respected for his clinical work but once took controversial positions on HIV testing. He has no apparent experience running a governmental public-health agency.

Robert Redfield, a professor of medicine at the University of Maryland School of Medicine, has emerged as the leading candidate to be CDC director, according to several public health sources.

Redfield, who did not respond to a call and email seeking comment, has repeatedly surfaced as a candidate for the top job at both the CDC and the National Institutes of Health when Republicans have been in control in Washington.

The CDC director’s job has been vacant since Jan. 31, when former Georgia public health commissioner Brenda Fitzgerald resigned after serving only half a year. She was unable to divest from “complex financial interests” in a “definitive time period,” according to a statement from the Health and Human Services Department. Fitzgerald had also purchased shares in a tobacco company shortly after becoming CDC director. HHS Secretary Alex Azar accepted her resignation two days after he was sworn in.

HHS spokesman Matt Lloyd said Friday evening that the department had no comment.

A former Army physician and leading AIDS researcher, Redfield is director of clinical care and research at the Institute of Human Virology at the University of Maryland medical school in Baltimore. The biography posted on the university website describes his main focus as clinical research and care of chronic human infections, especially HIV/AIDS.

He oversees a major clinical program providing HIV care and treatment to more than 6,000 patients in the Baltimore-Washington region and a care program that is part of the President’s Emergency Plan for AIDS Relief, known as PEPFAR. Redfield has served as a member of the Presidential Advisory Council on HIV/AIDS.

In the early 1990s, while he was an AIDS researcher in the Army, Redfield stirred controversy over an experimental AIDS vaccine that ultimately failed. He had been known as a strong supporter of mandatory patient testing for HIV during the 1980s, at a time before effective treatments were available and intense stigma surrounded people infected with the virus, according to advocates and researchers.

“The controversy in the 1980s was that some of the policies he advocated and some of the organizations he was associated with were not embracing sound public health approaches to the AIDS epidemic and were stigmatizing of those who were infected,” said Jeffrey Levi, who was executive director of the National Gay and Lesbian Task Force and later became deputy director of the Office of National AIDS Policy under President Bill Clinton.

“The context that people have to remember is that during this time, people could be fired for having HIV; they could lose their health insurance for having HIV,” he said. “That’s why there was so much furor.”

Redfield was closely linked to a controversial and unsuccessful effort in Congress in 1991 to require HIV testing of health-care professionals who perform invasive procedures. The bill was introduced by Rep. William E. Dannemeyer, a California Republican who was one of the most conservative members of Congress.

The researcher also clashed with AIDS treatment advocates over whether to collect the names of those who tested positive rather than using anonymous identifying codes, according to a 2002 report in the Atlanta Journal-Constitution when he was among the candidates being considered to be CDC director under President George W. Bush. That job went to Julie Gerberding.

With infectious disease outbreaks on the rise, the CDC plays a critical role in detecting, preventing and controlling their spread. Public health experts say it’s essential that the next director understand public health, be tested in a public health emergency and have some familiarity with the Atlanta-based agency, which is responsible for issues including the world’s most dangerous organisms, chronic diseases such as diabetes and obesity, and birth defects caused by the mosquito-borne Zika virus.

“You want someone leading the organization who has been tested,” said John Auerbach, president and chief executive of Trust for America’s Health, a public health nonprofit. “You wouldn’t want them to spend a year of their lives learning about the agency they’re overseeing. In a crisis, we need someone who can hit the ground running.”

The position does not require Senate confirmation, but Democrats, led by Sen. Patty Murray (Wash.), the ranking Democrat on the Senate Health, Education, Labor and Pensions Committee, sent a letter to the White House this month saying they intend to “thoroughly scrutinize” any candidate to ensure he or she is an “upstanding steward” of public health. The letter listed more than a dozen criteria, including prioritizing science over ideology, resolving any conflicts of interest and leading the federal government in engaging in critical evidence- and science-based research and policymaking.

Several other candidates with strong public health backgrounds were among those under consideration earlier, but Redfield's name emerged as the top contender in the last two weeks, said the sources, who spoke on the condition of anonymity because of the sensitivity of the issue.

Redfield is respected in his field, according to one researcher, but is known to be very religious. “That over-religiousness turns off some in the scientific and public health community,” the scientist said.

Alice Crites contributed to this report.

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