Tensions between Donald Trump and Elon Musk exploded into public view Thursday, as the US president said he was “very disappointed” by his billionaire former aide’s criticisms and Musk hit back in real time on social media.

“Look, Elon and I had a great relationship. I don’t know if we will anymore,” Trump told reporters in the Oval Office after Musk slammed his tax and spending mega-bill as an “abomination”.

The world’s richest man responded by live-posting on his X social media platform as Trump spoke on television, saying that the Republican would not have won the 2024 election without him and slamming him for “ingratitude.”

In an extraordinary rant as visiting German Chancellor Friedrich Merz sat mutely beside him, 78-year-old Trump unloaded on SpaceX and Tesla boss Musk in his first comments on the issue.

“I’m very disappointed, because Elon knew the inner workings of this bill better than almost anybody sitting here … all of a sudden, he had a problem,” Trump said when asked about Musk.

The clash comes less than a week since Trump held a grand Oval Office farewell for Musk as he wrapped up his time leading the cost-cutting Department of Government Efficiency (DOGE).

South African-born Musk, 53, hit back minutes later, saying Trump’s claims he had advance sight of the bill were “false”.

“Whatever,” he added above a video of Trump saying Musk was upset about the loss of subsidies for electric vehicles.

Musk then ratcheted up the public spat even further, saying the Republican would have lost the election without his support. He was the biggest donor to Trump’s campaign, to the tune of nearly $300 million.

“Without me, Trump would have lost the election,” Musk said on X. “Such ingratitude.”

Tesla shares fell sharply on Wall Street, down eight percent, after his comments, in a sign of the huge stakes for a falling out between the world’s richest man and its most powerful.

Later, Musk uploaded a poll to his X account asking his followers whether or not it was time to start a new political party that “actually represents the 80 per cent in the middle”.

An overwhelming majority of his followers voted “yes” as of 11:30pm.

After his meeting, Trump took to his own platform, Truth Social, and wrote posts stating that he asked “crazy” Musk to leave and that the his administration could save billions of dollars by cutting Musk’s government contracts.

“I took away his EV mandate that forced everyone to buy electric cars that nobody else wanted (that he knew for months I was going to do!), and he just went crazy!” the US president wrote in one post, adding that he asked Musk to leave because he was “wearing thin”.

A while later, Musk responded by calling Trump’s remarks “an obvious lie”.

“So sad,” he wrote on X, reposting a screenshot of Trump’s post.

In a separate post, Trump wrote: “The easiest way to save money in our budget, billions and billions of dollars, is to terminate Elon’s governmental subsidies and contracts. I was always surprised that Biden didn’t do it!”

‘A little make-up?’

A wistful-sounding Trump took reporters through the break-up with Musk on live television, in what at times sounded more like a therapy session than a meeting with a foreign leader.

Trump talked about Musk’s farewell appearance in the Oval Office on Friday, when he turned up with a black eye that he said was caused by a punch from his son.

Musk at the time was also facing reports of drug use on the Trump campaign trail.

“You saw a man who was very happy when he stood behind the Oval desk, and even with the black eye. I said, you want a little makeup? We’ll get you a little makeup,” Trump said.

“But he said, ‘No, I don’t think so,’ which is interesting and very nice. He wants to be who he is.”

Trump said he could understand why Musk was upset with some steps he had taken, including withdrawing a nominee to lead the Nasa space agency whom the tech tycoon had backed.

Through it all, the visiting German chancellor sat silently.

Merz had prepared to avoid a repeat of the ambushes that Trump unleashed on the Ukrainian and South African presidents in the Oval Office — but in the end it was Musk that the US president ambushed.

At the centre of the bitter row is Trump’s “big, beautiful bill” on tax and spending.

The centrepiece of his domestic agenda, it aims to continue tax cuts from his first term — and could define his second term and make or break Republican prospects in the 2026 midterm elections.

Musk, however, called it a “disgusting abomination” on Tuesday, on the grounds that it will increase the US deficit. A day later, the magnate called for Republicans to “kill the bill”, and for an alternative plan that “doesn’t massively grow the deficit”.