Donald Trump’s sweeping domestic policy bill has careened into an Elon Musk opposition threatens-shaped brick wall, complicating its passage into law and risking a schism between the most powerful man in the world and the wealthiest.

The US president’s “big, beautiful bill” — the center piece of his domestic agenda — could define his second term and make or break Republican prospects in the 2026 midterm elections.

But the package is getting a rough ride in Congress over proposals to fund an extension of his 2017 tax cuts by piling on debt and cutting social welfare for the poorest Americans.

Enter tech billionaire Musk, who dropped a nuclear bomb on the 1,100-page blueprint at a crucial stage in negotiations Tuesday, calling it a “disgusting abomination.”

And on Wednesday he called for Republicans to “kill the bill,” and for an alternative plan that “doesn’t massively grow the deficit.”

In its latest estimate released Wednesday, the non-partisan Congressional Budget Office said the bill would add $2.4 trillion to US debt by 2034.

Musk, who last week ended his brief advisory tenure as Trump’s cost-cutter-in-chief, tore into the bill in a prolonged denouncement.

The South African-born tycoon has voiced concerns before, but his language was much more combative, coming across as a declaration of war on the Republican Party, if not Trump himself.

The White House brushed off the criticism, saying Trump “already knows where Elon Musk stood,” but the remarks will likely have gotten under the president’s skin.

‘Lennon and McCartney’

The stakes could hardly be higher for Trump, who has made clear, with signature hyperbole, that he sees his bill as “arguably the most significant piece of legislation that will ever be signed.”

He has yet to respond personally to Musk’s social media rant — sustained over six hours and 13 posts on Tuesday and still going well into Wednesday.

Musk Opposition Threatens Powerful Passage of Trump Bill

But Washington watchers aren’t necessarily expecting a public falling-out.

Behind the scenes, a careful circling of the wagons is underway, with pro-Trump pundits under orders to refrain from trashing Musk and to instead frame his broadside as what Politico called “principled self-interest.”

Still, for analysts contacted by AFP, there may be choppier waters ahead.

“It’s the Lennon and McCartney of modern politics. Two egos, one spotlight, and a fragile alliance built on mutual benefits,” said Evan Nierman, the founder and CEO of global crisis PR firm Red Banyan.

“The moment either one sees more upside in conflict than cooperation, the breakup goes public.”

But political consultant and former Senate aide Andrew Koneschusky, a key player in negotiations over Trump’s 2017 tax cuts, believes the Republican leader has nothing to gain by biting back.

“Musk has more money. Musk’s megaphone, X, is bigger than Trump’s. And Musk was deeply embedded in the administration for months,” he told AFP.

“There’s no telling what Musk heard or saw that could be embarrassing or problematic for the administration if the two were to go to war.”

‘Bromance’

Crucially, Musk slammed right-wing lawmakers who voiced concerns over debt but cleared the bill for Senate consideration anyway — almost the entire 220-strong House Republican group.

Musk, who spent around $280 million getting Trump elected, undoubtedly has the cash to make his mark on the midterms.

And the de facto leader of America’s “tech bro” community demonstrated his political firepower with a single tweet in December that blew up a government funding bill that had enjoyed bipartisan support.

His take on the deficit implications of Trump’s proposals is evidenced by copious independent research and he was immediately backed by some fiscal hawks in the Senate.

Continued interventions by Musk could be an ongoing headache for Trump, as he bids to shepherd his policy priorities through razor-thin Republican majorities in Congress.

But cheerleaders of the package — and independent analysts contacted by AFP — believe the Tesla magnate may discover that his celebrity in Trump world relies on the say-so of its mercurial chieftain.

“Musk may have influenced in December when his bromance with Trump was in full bloom,” said Donald Nieman, a political analyst and professor at Binghamton University in New York State.

“But his break with Trump and his massive unpopularity with voters makes it easy for lawmakers to ignore him. If anything, it helps Trump by distancing him from a man who has become a pariah.”