President Biden is expected to nominate former senator Bill Nelson to be the next administrator of NASA, according to multiple people with knowledge of the matter.

If approved by the Senate, Nelson would be the second consecutive NASA chief to come from Congress and would give NASA a leader with close ties to the Oval Office. Nelson was a key Biden supporter during the presidential campaign and has a long personal relationship with the president.

The announcement could come as early as Friday, according to the people briefed on the matter who were not authorized to speak publicly ahead of the official announcement. The White House is strongly considering Pamela Melroy, a former NASA astronaut and a retired Air Force colonel, as deputy administrator, but that decision is not yet final, officials said.

Nelson flew in the space shuttle in 1986 and oversaw NASA’s space programs while in Congress. He is knowledgeable and enthusiastic about space and NASA, an agency he has long cherished. But the choice is disappointing to many who were hopeful that the next NASA administrator would be a woman, the first to serve in the agency’s top position.

Nelson, a Democrat from Florida, has long been an advocate for space — a rarity among members of Congress. NASA and its contractors have been an important source of jobs in Florida, where the Kennedy Space Center is located. Huge crowds have flocked to the state for decades to watch launches.

While in the Senate, Nelson was a staunch supporter of NASA’s Space Launch System, the troubled heavy-lift rocket that Congress mandated after the Obama administration canceled a previous rocket and spacecraft program, called Constellation, that was way over budget and behind schedule. Like its predecessor, the SLS rocket is years behind schedule and overbudget and has yet to fly.

That stance has made proponents of the commercialization of space wary at a time when NASA has embraced the expanding capabilities of the private sector. NASA relies on SpaceX, for example, to fly its astronauts to and from the International Space Station under NASA’s “commercial crew” program and is looking to the private sector to help its quest to return to the moon.

While Nelson, 78, is a well-known champion for NASA, many were hoping for a new generation of leadership to carry the agency into a new era. “It’s time for a female administrator,” tweeted Wayne Hale, a former NASA space shuttle program manager who was the flight director for 40 missions. “Plenty of qualified candidates.”

But since then the commercial sector has gone a long way toward changing the minds of officials who were once skeptical, and people close to Nelson have said he is enthusiastic about the promise of the commercial industry.

The nomination comes at a critical time for NASA. It recently landed the Perseverance rover on Mars, and it is pushing to return astronauts to the moon for the first time since the last Apollo mission landed there in 1972. A key test of the SLS system is scheduled Thursday.

Recently, White House press secretary Jen Psaki said the Biden administration supports the effort, known as Artemis, continuing a Trump administration program that Nelson would now oversee.

As a key member of the Senate Commerce, Science and Transportation Committee, which oversees NASA, Nelson took aim at President Donald Trump’s nominee for NASA administrator, arguing that Jim Bridenstine, a Republican congressman from Oklahoma, was not qualified in part because of his political ties.

“The NASA administrator should be a consummate space professional who is technically and scientifically competent, and is a skilled executive,” he said during Bridenstine’s confirmation hearing. “This committee has heard me say many times: NASA is not political. The leader of NASA should not be political. The leader of NASA should not be bipartisan; the leader of NASA should be nonpartisan.”

After Bridenstine was confirmed by a narrow party-line vote, he worked diligently with Democrats and Republicans alike. And he appointed Nelson to a NASA advisory committee, calling him a “true champion for human spaceflight.”

In 1986, as NASA was gearing up to fly civilians in the space shuttle — first a teacher, then a journalist — Nelson, then a member of the House, was able to fly first, joining the crew of NASA astronauts. Among them was Charlie Bolden, whom Nelson later pushed to become administrator, rejecting other names floated by the Obama administration.

Lori Garver, who served as NASA deputy administrator under President Barack Obama, said the choice of Nelson was “an ironic turn of events considering he blocked President Obama’s top nominees for the job in 2009 and then led the congressional effort that dismantled the Obama-Biden strategy and proposed budget, created the Space Launch System, reinstated Orion and cut funding for technology and commercial crew.”

She added that Nelson will need to understand why the SLS rocket “has cost so much more than projected.” But she said he “has already had more influence on NASA than anyone in recent memory, so he has plenty of experience and should be able to hit the ground running.”

Given his deep ties in Congress and his long interest in space, Nelson is expected to be confirmed.