WASHINGTON -- US President Donald Trump bid farewell to Elon Musk in the Oval Office on Friday, after the billionaire announced his decision to step back from his role at the Department of Government Efficiency (DOGE).

"I just want to say that Elon has worked tirelessly, helping lead the most sweeping and consequential government reform programme in generations," said Trump.

Trump credited Musk with "a colossal change in the old ways of doing business in Washington" and said some of his staff would remain in the administration.

"I look forward to continuing to be a friend and advisor to the president," Musk told reporters after Trump handed a golden key as a gift.

Having spent approximately $300 million?to back Trump's presidential campaign and other Republicans, Musk recently said that he plans to cut his political spending substantially, because "I think I've done enough."

In an interview with CBS News on Tuesday, Musk criticized Trump's "One, Big, Beautiful Bill Act," describing the legislation, a mix of tax cuts and enhanced immigration enforcement, as a "massive spending bill" that increases the federal deficit and "undermines the work" of DOGE.