Elon Musk recently swapped his Dark MAGA hat and government “Tech Support” garb for his old “Occupy Mars” T-shirt, a reference to his rocket company SpaceX’s mission to colonize the red planet.

He embarked on a media blitz, granting interviews to news outlets that he had previously avoided and saying that he was focused on SpaceX and discussing his electric automaker Tesla.

And on social media, he posted that he was once again spending “24/7 at work” and sleeping in his companies’ factories and server rooms.

As Mr. Musk steps away from Washington and his Department of Government Efficiency, President Trump’s “first buddy” is shifting back to his role as a business titan. But that move is not likely to come easy after Mr. Musk spent months backing Mr. Trump’s presidential campaign and dismantling parts of the federal government, raising concerns that he had become an absentee leader at his various enterprises, including SpaceX, Tesla, the artificial intelligence company xAI and the social media platform X.

Mr. Musk’s time in government has been a decidedly mixed bag for his business empire. Tesla is particularly vulnerable after Mr. Musk’s popularity nose-dived when he slashed government jobs. Tesla dealerships became the target of protests as sales and profit fell. What’s more, the Republican budget bill now before the Senate would gut subsidies and policies that promote electric vehicles. Tesla’s stock has dropped about 14 percent this year, wiping around $180 billion off its market value.

Some of Mr. Musk’s companies have benefited from his proximity to the White House, with Mr. Trump at one point promoting Tesla cars on the White House lawn and SpaceX harvesting more government tie-ups with Starlink, its satellite internet service. X remains a powerful megaphone for Mr. Musk’s and Mr. Trump’s supporters. And Mr. Trump is a valuable ally with policy power who oversees agencies that regulate Mr. Musk’s businesses.