Washington DC - Far-right billionaire Elon Musk may be President Donald Trump's biggest supporter in 2025, but their relationship was apparently very different at the end of the Republican's first term.

A person within earshot of an Oval Office meeting between the two in 2020 regarding a planned Tesla factory in Mexico told Politico that they had heard Musk call Trump a "f***ing moron" behind his back.

Musk had met with Trump's son-in-law Jared Kushner and was then hosted by Trump's then-deputy director of the White House Office of Public Liaison, Tim Pataki.

"We walk into the Oval, and he kind of looks around, and he's looking around," the source told Politico. "He's like, 'Gosh, I tell you. I mean, I was just in China and man, their palaces just make the White House kind of look more like an outhouse.'"

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In 2022, Trump also had some nasty words to say about Musk, taking to Truth Social to declare that without subsidies "he'd be worthless."

"I could have said, 'drop to your knees and beg,' and he would have done it," the added.

Later, Trump criticized Musk's behavior at a 2024 Butler, Pennsylvania rally, wondering aloud, "What the f*** is wrong with this guy?"

Musk and Trump have since settled their differences, but speculation remains as to how long their alliance will last.

Trump looked noticeably unhappy when, earlier this month, Musk brought his toddler into the Oval Office during a joint press conference.