President Trump and the world’s richest man, Elon Musk, traded jabs and uppercuts Tuesday, with each landing blows in a battle the two have engaged in since they fell out last month. 

Mr. Trump threatened to sic the Department of Government Efficiency — a cost-cutting agency Mr. Musk helped establish during his time working with the administration earlier this year — on Mr. Musk to investigate his businesses, including SpaceX.  

“We might have to put DOGE on Elon, you know. You know what DOGE is? DOGE is the monster that might have to go back and eat Elon. Wouldn’t that be terrible? He gets a lot of subsidies,” he told reporters on the White House lawn before heading to Florida to visit the new immigration detention center in a remote area of the Everglades, surrounded by alligator-filled swamps.

“Elon may get more subsidy than any human being in history, by far, and without subsidies, Elon would probably have to close up shop and head back home to South Africa,” the president said.

Mr. Musk, who was inseparable from Mr. Trump for months — even living at the White House during his time running DOGE — was not cowed by the threat. “So tempting to escalate this,” he wrote on X Tuesday. “So, so tempting. But I will refrain for now.”

Mr. Trump’s comments come on the heels of Mr. Musk’s outspoken criticism of the administration’s spending plans. He has denounced the president’s “big beautiful bill,” suggesting that its provisions would raise the national debt to unsustainable levels. On X, Mr. Musk referred to the bill as a “disgusting abomination” and claimed it represents reckless spending by what he called “The PORKY PIG PARTY!!”  

The billionaire did not stop at this criticism, warning lawmakers they could face consequences at the ballot box if they supported the bill. “Every member of Congress who campaigned on reducing government spending and then immediately voted for the biggest debt increase in history should hang their head in shame!” Mr. Musk wrote, pledging to challenge those lawmakers in upcoming primary races.  

Asked why the two have fallen out, Mr. Trump said of Mr. Musk, “He’s upset that he’s losing his EV mandate and he’s upset. He’s very upset about things. But he could lose a lot more than that. I can tell you right now, Elon can lose a lot more than that.”

“And you know what? When you look at it, who wants, not everybody wants an electric car. I don’t want an electric car. I want to have maybe gasoline, maybe electric, maybe a hybrid, maybe someday a hydrogen. You have a hydrogen car. It has one problem if it blows up,” Mr. Trump said.

“I campaigned for this thing for two years. I never understand why he did what he did, but he’s not going to get his mandate and he better be careful. He might not get anything else,” the president added.

The feud marks a stark departure from the earlier alliance of Messrs. Musk and Trump. Earlier this year, Mr. Musk served as the head of DOGE, where he led initiatives to streamline government expenses. Mr. Trump even awarded Mr. Musk a ceremonial gold key to the White House in recognition of his efforts.  

However, the relationship soured when Mr. Trump unveiled his sweeping budget bill, which Mr. Musk publicly opposed. Mr. Musk’s resistance intensified after reports emerged that the bill would terminate tax incentives for electric vehicles, a key revenue driver for Tesla.  

Mr. Musk’s rebuke of the administration appears to be having tangible effects. On Tuesday, Tesla’s stock price fell 7.5 percent as markets reacted to the ongoing tension between Mr. Musk and the president.  

Meanwhile, Mr. Musk has floated the idea of establishing a third political party, the “America Party,” should Mr. Trump’s budget bill be approved by Congress. “If this insane spending bill passes, the America Party will be formed the next day,” Mr. Musk tweeted.

The proposed budget bill is under debate in Congress, where Mr. Trump’s Republican Party holds a majority in both chambers. The bill includes increased funding for border security, defense, and energy projects, offset by cuts to Medicare and food assistance programs.