After Trump pulled NASA nomination, Musk ally Jared Isaacman says stint in politics was 'thrilling'

Inspiration4 mission commander Jared Isaacman, founder and chief executive officer of Shift4 Payments, stands for a portrait in front of the recovered first stage of a Falcon 9 rocket at Space Exploration Technologies Corp. (SpaceX) on February 2, 2021 in Hawthorne, California.Patrick T. Fallon | Afp | Getty ImagesDays after his nomination for NASA was pulled by President Donald Trump, Jared Isaacman told investors in his payments company Shift4 that his "brief stint in politics was a thrilling experience."Isaacman said in the letter that he was resigning as CEO of Shift4, which he founded in 1999 at age 16, and will assume the role of executive chairman. He had been planning to leave the company if his nomination was confirmed by the Senate. But it never got that far.In a post on Truth Social over the weekend, Trump said that he was withdrawing Isaacman's nomination "after a thorough review of prior associations." The president didn't indicate what those associations were, though some reports have suggested that it was a reference to Isaacman's prior donations to Democrats."Even knowing the outcome, I would do it all over again," Isaacman wrote in the letter.In an episode of the All-In podcast that went live on Wednesday, Isaacman, who has close ties to Elon Musk, indicated that his past donations weren't likely the reason for Trump's decision. He noted that his donations were public long before he was nominated, and he described himself as "right-leaning" and a supporter of the president's agenda."I don't want to play dumb on this," he said. "I don't think the timing was much of a coincidence."The timing he was referencing was Musk's official exit from his government service work at the end of May.In addition to his career in finance, Isaacman has led two private spaceflights through Musk's SpaceX, in 2021 and 2024, commanding crews on multiday trips around the Earth. Shift4 also invested $27.5 million in SpaceX, according to a 2021 filing.Musk became one of Trump's biggest backers and, until last week, was leading the administration's Department of Government Efficiency (DOGE), tasked with slashing the size of the federal government. With Musk's official time as a "special government employee" coming to an end because of the 130-day limit, the world's richest person has quickly turned into a vocal critic of Trump's massive tax-cut bill.On Wednesday, Musk ramped up his attacks on the bill that Trump is pushing Congress to pass, claiming it will condemn America to "debt slavery" and urging lawmakers to "KILL the BILL." A day earlier, Musk slammed what Trump has dubbed the "big, beautiful bill" as a "disgusting abomination."Trump's decision to pull Isaacman's nomination came before Musk's latest tirade. But Musk had been distancing himself from the administration in recent weeks."You got one person," Isaacman said on All-In, referring to Trump as the one making the call. He said he doesn't "know what the trigger was or wasn't" and said he doesn't "fault the president for it."The White House didn't immediately respond to a request for comment.At Shift4, Isaacman said in Wednesday's letter that he'll be succeeded as CEO by Taylor Lauber, who started at the company in 2018 and has been serving as president."I have been working since I was a teenager and not planning to stop now," Isaacman wrote. "I love this company, the strategy and our team. As the largest shareholder, I am eager to continue contributing where I believe my efforts will have the most impact." — CNBC's Lora Kolodny and MacKenzie Sigalos contributed to this report.WATCH: Elon Musk slams Trump's spending bill