WASHINGTON: Billionaire Elon Musk plunged on Tuesday (Jun 3) into the congressional debate over President Donald Trump's sweeping tax and spending bill, calling it a "disgusting abomination" that will increase the federal deficit.

Several fiscally conservative Republicans in the US Senate supported the views Musk expressed in social media posts, which could complicate the bill's path to passage in that chamber.

"I'm sorry, but I just can't stand it anymore," Tesla and SpaceX CEO Musk wrote in a post on his social media platform X. "This massive, outrageous, pork-filled Congressional spending bill is a disgusting abomination."

He added: "Shame on those who voted for it: you know you did wrong. You know it."

Musk's comments hit a nerve. Republican deficit hawks have expressed concerns about the cost of the bill, which would extend the 2017 tax cuts that were Trump's main legislative accomplishment, while boosting spending on the military and border security.

The House of Representatives passed it by one vote last month, after the nonpartisan Congressional Budget Office said the measure would add US$3.8 trillion to the federal government's US$36.2 trillion in debt.

The Senate, also controlled by Trump's Republicans, aims to pass the "One Big Beautiful Bill Act" in the next month, though senators are expected to revise the House version.

Republicans on the Senate Finance Committee, which oversees tax policy, are due to meet with Trump at the White House on Wednesday afternoon to discuss making the bill's business-related tax breaks permanent, according to Senator Steve Daines, a panel member. Analysts have warned that such a move would greatly increase the measure's cost.

Republican Senate Majority Leader John Thune said he disagreed with Musk's assessment about the cost of the bill and stood by the goal of passage by Jul 4.

"We have a job to do - the American people elected us to do. We have an agenda that everybody campaigned on, most notably the president of the United States, and we're going to deliver on that agenda," the South Dakota lawmaker told reporters.

Republican House Speaker Mike Johnson also dismissed Musk's complaints, telling reporters, "my friend Elon is terribly wrong."

TEST OF INFLUENCE

Musk's loud opposition to a bill that Trump has urged Republicans to pass presents a test of his political influence a week after leaving his formal role in the administration as a special government employee with the Department of Government Efficiency came to an end. As DOGE chief, he upended several federal agencies but ultimately failed to deliver the massive savings he had sought.

The richest person in the world, Musk had spent nearly US$300 million to back Trump's presidential campaign and other Republicans in last year's elections. But he has said he would cut his political spending substantially while returning to his role as Tesla CEO.

The White House dismissed Tuesday's attack, just as Trump dismissed earlier Musk complaints about the legislation.

"Look, the president already knows where Elon Musk stood on this bill," spokeswoman Karoline Leavitt said at a White House briefing. "It doesn't change the president's opinion. This is one big, beautiful bill, and he's sticking to it."

REPUBLICAN DISAGREEMENTS

Senate Republicans were divided about the bill even before Musk's missives. Deficit hawks are pushing for deeper spending cuts than the US$1.6 trillion over a decade in the House version, while another coalition of rural-state Republicans are pushing to protect the Medicaid healthcare program for low-income Americans.

One of the hawks, Senator Mike Lee, called on party members to use the Trump bill and future spending measures to reduce the deficit.

"We must commit now to doing so, as this is what voters justifiably expect - and indeed deserve - from the GOP Congress," the Utah Republican said on X while reposting Musk's message.

Republicans have a 53-47 seat majority in the Senate and can afford to lose support from no more than three members, if they expect to pass the legislation with a tie-breaking vote from Vice President JD Vance by a July 4 deadline.

Another hardliner, Senator Ron Johnson, predicted that lawmakers would not be able to meet the deadline and secure an adequate number of cuts.

Lee and Johnson are among at least four Senate hardliners demanding that the bill be changed to restrict the growth of the debt and deficit.

The faction of party lawmakers determined to limit spending cuts to project Medicaid beneficiaries and business investments in green energy initiatives is of similar size.

"I certainly have an interest in making sure people with disabilities are not harmed. But also, there's the broad issue of how does it affect hospital reimbursements," Senator Jerry Moran told reporters.

"There's a set of my colleagues who are pushing to do more. And so it turns on how do you get the votes to pass a bill," the Kansas Republican said.

Other Senate Republicans said lawmakers may have to look elsewhere to boost savings, including the possibility of leaving Trump's much touted tax break proposals for tips, overtime pay and Social Security benefits for later legislation.

"Those are all Democrat priorities. I'm not sure why we shouldn't be doing that in a potential bipartisan bill to create headspace for this bill," said Republican Senator Thom Tillis.

Musk calls Trump's tax-cut and spending bill 'a disgusting abomination'