Donald Trumps Mar-a-Lago club has been brimming in the last 48 hours with two kinds of people: those angling for a job in the president-elect’s incoming administration, and those trying to influence him into hiring their picks for the top spots.

But the one person who has loomed over it all and has exerted a great deal of influence is Elon Musk, according to multiple sources. The tech billionaire has been seen at the resort in Palm Beach, Florida, almost every day since Trump won the election  last week, dining with him on the patio some evenings and hanging out with his family Sunday at the golf course.

Musk has been in the room when multiple world leaders have phoned Trump, and he’s weighed in on staffing decisions, with the SpaceX and Tesla CEO even making clear his preference for certain roles.

In one instance, Musk was with Trump at Mar-a-Lago when Ukrainian President Volodymyr Zelensky  called to congratulate the president-elect the day after the election, according to a source briefed on the call. Trump put the call on speaker, and Zelensky thanked Musk for his help providing communications to Ukraine through the billionaire’s Starlink internet service.

On Sunday, Musk waded into the GOP Senate leadership fight, endorsing Sen. Rick Scott after the Florida Republican swiftly backed Trump’s demand that anyone vying to be leader support recess appointments for his nominees — a way for presidents to attempt to bypass Congress that Senate Democrats could essentially block.

Musk is not only close to Trump but also with his transition co-chair, Howard Lutnick — the billionaire CEO of financial services firm Cantor Fitzgerald who is leading the personnel side of the transition.

Sources have described Trump as enamored with Musk.

“We have to protect our geniuses, we don’t have that many of them,” the president-elect said during his victory speech early Wednesday morning.

While Musk himself is not formally expected to take a position in Trump’s administration, he doesn’t really need to, one source said, noting the X owner is having just as much influence from the outside.

While Trump and Musk had publicly pitched the latter leading an efficiency commission to slash spending inside the federal government, CNN reported Thursday that a source familiar with the conversations around Musk said it seemed unlikely he would even want a full-time government position, given what that would mean for his role in the companies he helms.

Instead, it seemed more plausible that Musk would be appointed to a blue-ribbon committee, where he would still have enormous access but would not be subject to government ethics rules, which would require him to divest or put assets in a blind trust to avoid conflicts of interest.

As of mid-October, Musk had donated nearly $119 million to a political action committee he set up to support Trump, according to Federal Election Commission filings. He also appeared with Trump at rallies and hosted a friendly interview with him on X, his social media platform.

Musk’s big bet on Trump paid near-immediate dividends. The day after the election, investors sent shares of Tesla up nearly 15%. That lifted the value of the 411 million shares that Musk owns outright by more than $15 billion and marked a two-year high for Tesla shares as a whole.