Washington DC - President Donald Trump on Wednesday tapped Transportation Secretary Sean Duffy to serve as interim head of space agency NASA, weeks after pulling the nomination of a tech billionaire who was an ally of SpaceX boss Elon Musk.

"I am pleased to announce that I am directing our GREAT Secretary of Transportation, Sean Duffy, to be Interim Administrator of NASA," Trump posted on his Truth Social platform, praising Duffy's work on modernizing the country's air traffic control system.

"He will be a fantastic leader of the ever more important Space Agency, even if only for a short period of time," Trump said.

On May 31, Trump yanked his nomination of Jared Isaacman – the first private astronaut to conduct a spacewalk – to lead NASA.

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Isaacman, a 42-year-old online payments entrepreneur, had emerged as a leading figure in commercial spaceflight through his high-profile collaborations with Musk's SpaceX.

"I was surprised to learn that he was a blue blooded Democrat, who had never contributed to a Republican before," Trump posted about Isaacman on July 6.

"I also thought it inappropriate that a very close friend of Elon, who was in the Space Business, run NASA, when NASA is such a big part of Elon's corporate life," he added.

Musk, the world's richest person, was almost inseparable from Trump as he headed the cost-cutting "Department of Government Efficiency," or DOGE, but the pair later fell out hard over the president's "big beautiful" domestic policy mega-bill.