The plan drew the approval of some prominent corporate figures, including Mark Cuban and the financier Anthony Scaramucci.

Trump appears increasingly annoyed by his former backer. From a post on Truth Social on Sunday:

I am saddened to watch Elon Musk go completely “off the rails,” essentially becoming a TRAIN WRECK over the past five weeks. He even wants to start a Third Political Party, despite the fact that they have never succeeded in the United States – The System seems not designed for them. The one thing Third Parties are good for is the creation of Complete and Total DISRUPTION & CHAOS, and we have enough of that with the Radical Left Democrats, who have lost their confidence and their minds!

Trump attributed Musk’s pique to the elimination of what the president called an electric vehicle mandate that would have eventually forced Americans to buy E.V.s. (There was never a federal mandate, but the recently passed legislation scrapped subsidies for E.V.s.)

Musk argued that he was more outraged by the cost of the bill, which the nonpartisan Congressional Budget Office estimates would add more than $3 trillion to the national debt. “What the heck was the point of @DOGE if he’s just going to increase the debt by $5 trillion??” Musk wrote on X, referring to the Department of Government Efficiency cost-cutting initiative he had spearheaded until May.

Shares in Tesla are down nearly 7 percent in premarket trading, as investors worry about potential retribution. (We’ve outlined the risks of Musk’s fights against Trump to his companies before; in short, many rely on government subsidies and contracts, and would be hurt by tighter regulations.) Here’s what the tech analyst and Tesla bull Dan Ives wrote to investors on Sunday:

With the autonomous future ahead and the AI Revolution in full force Musk/Tesla do not need to keep poking the bear as Trump can create more hurdles for Musk/Tesla/SpaceX over the coming years if this political battle gets nastier heading into mid-terms in 2026.

Treasury Secretary Scott Bessent added that Musk could feel pressure from Tesla’s board if he proceeds. “I imagine that those board of directors did not like this announcement on Sunday and will be encouraging him to focus on his business activities, not his political activities,” Bessent told CNN on Sunday.

(Whether that would come to pass — Tesla’s board has been criticized for being deferential to Musk — is unclear.)