Billionaire entrepreneur and private astronaut Jared Isaacman returned to the U.S. Senate on Wednesday, urging lawmakers to quickly move forward on his nomination to serve as NASA administrator — a nomination President Donald Trump withdrew earlier this year and then reinstated.

Speaking before the Senate Commerce, Science and Transportation Committee, Isaacman emphasized the urgency of having stable leadership at NASA as the agency prepares for its upcoming lunar mission. Transportation Secretary Sean Duffy has been serving as acting NASA chief since summer.

Isaacman, who has flown to orbit twice with SpaceX and conducted the first private spacewalk, told senators that sending astronauts around the moon early next year — the first crewed lunar voyage in more than 50 years — will be a major undertaking. He warned that losing ground to China in space could have serious strategic consequences.

Sen. Ted Cruz, who chairs the committee, echoed those concerns and said the U.S. must stay ahead in the new space race.

Isaacman was close to Senate confirmation in May before Trump abruptly pulled the nomination amid tensions with SpaceX founder Elon Musk. His renomination has revived the process, and Cruz hopes to finalize the appointment by year’s end.

Isaacman said the U.S. should pursue missions to both the moon and Mars simultaneously, and he supported reopening the lunar lander contract under NASA’s Artemis program. He stressed that NASA will rely on whichever company — SpaceX or Blue Origin — proves ready first, adding that competition is essential to American success in space.