Jared Isaacman, the private astronaut and Elon Musk ally who was removed from consideration to lead NASA earlier this year, met with acting NASA Administrator Sean Duffy this week as a candidate for leading the space agency, a NASA spokesperson said.

“Secretary Duffy and Jared Isaacman had an excellent meeting yesterday,” NASA press secretary Bethany Stephens said in a statement. “At President Trump’s direction, Secretary Duffy in his capacity as acting NASA Administrator is meeting with and vetting several candidates for the permanent role.”

Isaacman did not immediately respond to requests for comment.

Last year, then-president elect Donald Trump tapped Isaacman to lead NASA at the recommendation of Musk, the SpaceX CEO who had been an influential adviser to the president and sought to more closely align the U.S. space program with his goal of flying missions to Mars.

Isaacman, a billionaire SpaceX customer who flew to space twice on the company’s capsules, had spent months navigating the Senate confirmation process, balancing the Trump administration’s desire to focus on Mars with NASA’s multibillion-dollar strategy to return to the moon first in a geopolitical race with China.

But in May Trump pulled Isaacman’s nomination amid a high-profile falling out with Musk. Duffy, also the head of the U.S. Department of Transportation, was named acting NASA chief.