US President Donald Trump said Friday that Elon Musk had "lost his mind" but insisted he wanted to move on from the fiery split with his billionaire former ally.

The blistering public break-up between the world's richest person and the world's most powerful is fraught with political and economic risks all round.

Trump had scrapped the idea of a call with Musk and was even thinking of ditching the red Tesla he bought at the height of their bromance, White House officials told AFP.

"Honestly I've been so busy working on China, working on Russia, working on Iran... I'm not thinking about Elon Musk, I just wish him well," Trump told reporters aboard Air Force One en route to his New Jersey golf club late Friday.

Earlier, Trump told US broadcasters that he now wanted to focus instead on passing his "big, beautiful" mega-bill before Congress -- Musk's harsh criticism of which had sparked their break-up.

But the 78-year-old Republican could not stop himself from taking aim at his South African-born friend-turned-enemy.

"You mean the man who has lost his mind?" Trump said in a call with ABC when asked about Musk, adding that he was "not particularly" interested in talking to the tycoon.

Trump later told Fox News that Musk had "lost it."

Just a week ago Trump gave Musk a glowing send-off as he left his cost-cutting role at the so-called Department of Government Efficiency (DOGE) after four months working there.

'Very disappointed'

While there had been reports of tensions, the sheer speed at which their relationship imploded stunned Washington.

After Musk called Trump's spending bill an "abomination" on Tuesday, Trump hit back in an Oval Office diatribe on Thursday in which he said he was "very disappointed" by the entrepreneur.

Trump's spending bill faces a difficult path through Congress as it will raise the US deficit, while critics say it will cut health care for millions of the poorest Americans. 

The row then went nuclear, with Musk slinging insults at Trump and accusing him without evidence of being in government files on disgraced financier and sex offender Jeffrey Epstein.

Trump hit back with the power of the US government behind him, saying he could cancel the Space X boss's multi-billion-dollar rocket and satellite contracts.

Trump struck a milder tone late Friday when asked how seriously he is considering cutting Musk's contracts. 

"It's a lot of money, it's a lot of subsidy, so we'll take a look -- only if it's fair. Only if it's to be fair for him and the country," he said.

Musk apparently also tried to de-escalate social media hostilities.

The right-wing tech baron rowed back on a threat to scrap his company's Dragon spacecraft -- vital for ferrying NASA astronauts to and from the International Space Station.

And on Friday the usually garrulous poster kept a low social media profile on his X social network.

But the White House denied reports that they would talk.

"The president does not intend to speak to Musk today," a senior White House official told AFP. A second official said Musk had requested a call. 

Tesla giveaway?

Tesla stocks tanked more than 14 percent on Thursday amid the row, losing some $100 billion of the company's market value, but recovering partly Friday.

Trump is now considering either selling or giving away the cherry red Tesla S that he announced he had bought from Musk's firm in March.

The electric vehicle was still parked on the White House grounds on Friday. "He's thinking about it, yes," a senior White House official told AFP when asked if Trump would sell or give it away.

Trump and Musk had posed inside the car at a bizarre event in March, when the president turned the White House into a pop-up Tesla showroom after viral protests against Musk's DOGE role.

But while Trump appeared to hold many of the cards, Musk also has some to play.

His wealth allowed him to be the biggest donor to Trump's 2024 campaign, to the tune of nearly $300 million. Any further support for the 2026 midterm election now appears in doubt -- while Musk could also use his money to undermine Trump's support on the right.