WASHINGTON (AP) — For more than a year, the Food and Drug Administration lacked a permanent head when the agency was central in the battle against COVID-19. Once President Joe Biden nominated Dr. Robert Califf to head the agency, it took the Senate three months to confirm him.

The political battles over Califf's nomination highlight the difficulties that Biden faces in filling key positions throughout his administration.

The vacancies in high-ranking positions across the executive branch could put a drag on Biden's ability to fight the pandemic, implement the $1 trillion bipartisan infrastructure law and boost the economy with inflation levels at a 40-year high.

"Without leadership and experts, we've seen departments increasingly stressed," said Maya MacGuineas, president of the bipartisan Committee for a Responsible Federal Budget. "There is a struggle to get appropriations done, there is talk about defaulting on the debt ceiling," she said, adding that unfilled jobs affect the government's fiscal position and the president's overall agenda.

The nonprofit Partnership for Public Service, which works to make government more effective, points to 70 high-ranking positions across the government without a confirmed nominee, including at the Department of Health and Human Services, the Treasury Department and the Transportation Department.

The White House blames gridlock from Republicans in a sharply divided Senate, but it also has not submitted nominations for many of the open positions.

The White House says the Biden administration has nominated 569 people, of whom 302 have been confirmed and 247 are waiting to go through the confirmation process. That's out of 1,200 civilian positions requiring Senate confirmation.

In Biden's first year, the Senate confirmed 41% of his nominations, according to the Partnership for Public Service. In comparison, 75% of George W. Bush's nominees were confirmed in his first year, compared with 69% for Barack Obama and 57% for Donald Trump.

The group is calling for a reduction in the number of Senate-confirmed nominees, stating that vetting and disclosure requirements are increasingly complex, and delays in the Senate confirmation process grow with each transition.

"Would it be better if it could happen faster? Yes," said former Treasury Secretary Jack Lew. "Ideally the confirmation process would be streamlined." But he added that there needs to be accountability for these important positions and a process for questioning nominees about how they would do the job.

Lew was confirmed by the Senate less than two months after he was nominated by Obama.

What the vacancies mean for some of Biden's policy priorities:

CREATING FISCAL POLICY

At the Treasury Department, at least five Senate-confirmed positions are unfilled, including the undersecretary for international affairs and treasurer of the U.S.

A Treasury Department without an international affairs head will make Secretary Janet Yellen's hope to lead the implementation of a global corporate taxation agreement increasingly difficult.

Lew told The Associated Press that having Senate-confirmed people with prior policymaking and government experience on staff will at least fill in the gaps where vacancies exist.

"If you look at the Treasury team, starting at the very top, you have the secretary and and deputy secretary with deep experience in policymaking," he said. "You've got a lot of career talent, which makes transitions go more smoothly."

The key to filling empty seats, he said, "is getting the congressional process to work better."

FIGHTING THE PANDEMIC

At the Department of Health and Human Services, two major science agencies remain without permanent Senate-confirmed leadership at a time as the administration struggles with its communications on the pandemic and the country might be reopening.

One of the agencies is the FDA. Califf's nomination had stalled for months in the Senate in part due to his consulting work for pharmaceutical companies and allegations that he had failed to effectively regulate addictive opioids. He was narrowly confirmed last week to the post, which he had held briefly under Obama.

The National Institutes of Health is also missing a director, although budget uncertainty is currently a bigger concern, said Ellie Dehoney a top policy expert with Research!America, a nonprofit that advocates for national spending on health and medical research.

"They are constrained because they are under an old budget and they can't launch new programs very easily," she said.

Staff morale remains steady nonetheless. "What we have heard around NIH is a desire to stay and particularly to see through this pandemic," Dehoney said.

IMPLEMENTING INFRASTRUCTURE PLANS

At the Transportation Department, acting heads are in place at the Federal Highway Administration and the Federal Motor Carrier Safety Administration, two of the three agencies at the forefront of promoting roadway safety, even as the department launches a new national strategy to stave off record increases in traffic fatalities. The third agency, the National Highway Traffic Safety Administration, is awaiting full Senate confirmation of Steven Cliff, Biden's pick to head the agency, after a committee approved the nomination Feb. 2.

The department also lacks a nominee for head of the Pipeline Hazardous Materials Safety Administration and will soon have a vacancy as well for head of the Federal Aviation Administration after Stephen Dickson steps down on March 31.

At the highway agency, deputy administrator Stephanie Pollack, a former state transportation secretary in Massachusetts, is key in implementing provisions of Biden's new infrastructure law, such as helping to issue guidance to states on use of billions in highway money and distribute competitive grants to promote traffic safety.

At the motor carrier agency, which regulates the trucking industry, Biden lost his pick for administrator after Meera Joshi left to take a post in New York Mayor Eric Adams' administration. The department recently shifted its deputy assistant secretary for safety policy, Robin Hutcheson, to serve as the agency's acting administrator.

Jonathan Adkins, executive director of the Governors Highway Safety Association, which represents state safety offices, expressed concern about the ability of the acting heads to effectively get work done.

Acting leaders typically have fewer staff around them and tend to be less publicly visible, he said. Currently the motor carrier agency has a number of proposed truck safety regulations yet to complete and is also working on changes to ease congestion in the U.S. supply chain. The highway agency, meanwhile, stands at the forefront of prodding states and localities to embrace changes to road design and speed limits to help curtail deaths.

EXPLORING GUN CONTROL

Early in his presidency, Biden nominated David Chipman to lead the Bureau of Alcohol, Tobacco, Firearms and Explosives, but the former ATF agent and gun control advocate faced opposition in the Senate and was seen as one of the administration's most contentious nominees. The nomination was withdrawn.

The withdrawal continued a pattern for both Republican and Democratic administrations with the politically fraught position since it was made confirmable in 2006. Since then, only one nominee, former U.S. Attorney B. Todd Jones, has been confirmed. Jones made it through the Senate in 2013 but only after a six-month struggle. Jones was acting director when Obama nominated him in January 2013.

Trump's nomination of Chuck Canterbury, a former president of the Fraternal Order of Police, was withdrawn in 2020 over Republican concerns about his gun rights stance.

"Our collective view here is that the blocking of a fully qualified, experienced former ATF agent from serving in that role certainly is something Republicans didn't have to take the step to do, but here we are," said White House press secretary Jen Psaki. She did not blame Democrats, who also said they would not vote for him. "So, we have to nominate a new person. And when the president finds the right person, I'm sure he'll be prepared to do that."

MacGuineas, of the Committee for a Responsible Federal Budget, said a "failure to govern" is to blame for the slowed nomination process.

"People have been nominated who are too controversial to be nominated, or the White House knows they're going to be held up," she said. "The way we are organized right now is highly inefficient with Congress highly polarized."