The Biden administration has announced its nomination of Robert Califf to lead the Food and Drug Administration (FDA) after almost a year under an acting administrator.

The nomination of the former FDA head faces opposition from within the Democratic Party.

Califf previously worked at the agency's medical products and tobacco office under former President Barack Obama. He worked with then-Vice President Joe Biden on the Cancer Moonshot Initiative.

Outgoing acting administrator Janet Woodcock has shepherded the FDA since January. Under her tenure, the agency fully authorized three COVID-19 vaccines, the launch of a nationwide booster shot campaign and a campaign of reassuring the public of the benefits of vaccinations.

However, by serving only in an acting capacity, Woodcock lacked the weight to set FDA priorities or influence interagency or internal disagreements compared to confirmed counterparts like CDC Director Rochelle Walensky.

Shortly after his nomination was reported, Sen. Joe Manchin, D-W.Va., released a statement opposing Califf's candidacy over his ties to the pharmaceutical industry. He described Califf’s nomination as an “insult” to the families of those who lost a loved one to opioid abuse.

“I have made it abundantly clear that correcting the culture at the FDA is critical to changing the tide of the opioid epidemic. Instead, Dr. Califf's nomination and his significant ties to the pharmaceutical industry take us backwards not forward," said Manchin.

Manchin’s opposition is not new. In 2016, he opposed Califf when President Obama nominated him to the FDA and he was joined by Sen. Bernie Sanders, I-Vt., within the Democratic caucus in opposition.

Manchin was joined in his opposition by Sen. Richard Blumenthal, D-Conn., who told Politico that he, too, had "grave reservations" about Califf, but did not say he would vote against him.

After leaving government service, Califf worked with Google's parent company Alphabet. Before joining the FDA in 2015, ProPublica reported that Califf served as a consultant for a number of drug makers, including Johnson & Johnson, Merck and AstraZeneca.

Given Democrats’ razor-thin margin in the Senate, Manchin's opposition, together with possible other dissenters in the party, would necessitate support from Republican senators. This may not be an issue for Califf, who secured an 89-4 confirmation when he was first nominated in 2016.