President Donald Trump said Saturday he is pulling the nomination of billionaire Jared Isaacman to be NASA administrator, citing "a thorough review of prior associations."

Axar.az informs, citing NBC news, Trump, in a post on his social media platform Truth Social, did not elaborate on what associations he was referring to.

"After a thorough review of prior associations, I am hereby withdrawing the nomination of Jared Isaacman to head NASA," Trump said in the social media post. "I will soon announce a new Nominee who will be Mission aligned, and put America First in Space."

Trump in December said he was nominating Isaacman, a billionaire entrepreneur who has never been in federal government, as NASA administrator. At the time, Trump said that "Jared will drive NASA’s mission of discovery and inspiration."

White House spokesperson Liz Huston said earlier Saturday that “it’s essential that the next leader of NASA is in complete alignment with President Trump’s America First agenda.”

Isaacman has been to space twice, on commercial missions that he funded himself.

The news outlet Semafor first reported Saturday that the White House was expected to pull Isaacman’s nomination.

The move comes as Isaacman was approaching a possible confirmation vote. A cloture motion on his nomination, which ends debate, is eligible for a vote on Monday, according to the congressional calendar.

Isaacman, who founded the payment processing company Shift4 and serves as its CEO, on X responded to the withdrawal of his nomination with thanks, writing, "I am incredibly grateful to President Trump" and the Senate.

"The President, NASA and the American people deserve the very best--an Administrator ready to reorganize, rebuild and rally the best and brightest minds to deliver the world-changing headlines NASA was built to create," he wrote in the post on X Saturday night.