WASHINGTON — Elon Musk is criticizing the centerpiece of President Donald Trump’s legislative agenda, a significant fracture in a partnership that was forged during last year’s campaign and was poised to reshape American politics and the federal government.

The billionaire entrepreneur, who supported Trump’s candidacy with at least $250 million and has worked for his administration as a senior adviser, said he was “disappointed” by what the president calls his “big beautiful bill.”

The legislation includes a mix of tax cuts and enhanced immigration enforcement. While speaking to CBS, Musk described it as a “massive spending bill” that increases the federal deficit and “undermines the work” of his Department of Government Efficiency, known as DOGE.

“I think a bill can be big or it could be beautiful,” Musk said. “But I don’t know if it could be both.”

His CBS interview came out Tuesday night. Trump, speaking in the Oval Office on Wednesday, defended his agenda by talking about the delicate politics involved with negotiating the legislation.

“I’m not happy about certain aspects of it, but I’m thrilled by other aspects of it,” he said.

Trump also suggested that more changes could be made.

“We’re going to see what happens,” he said. “It’s got a way to go.”

Republicans recently pushed the measure through the House and are debating it in the Senate.

Musk’s concerns are shared by some Republican lawmakers. Wisconsin Sen. Ron Johnson said he was “pretty confident” there was enough opposition “to slow this process down until the president, our leadership, gets serious” about reducing spending. Speaking at a Milwaukee Press Club event on Wednesday, he added that there was no amount of pressure Trump could put on him to change his position.

Speaker Mike Johnson has asked senators to make as few changes to the legislation as possible, saying that House Republicans reached a “very delicate balance” that could be upended with major changes. The narrowly divided House will have to vote again on final passage once the Senate alters the bill.

On Wednesday, Johnson thanked Musk for his work and promised to pursue more spending cuts in the future, saying “the House is eager and ready to act on DOGE’s findings.”

The White House is sending some proposed rescissions, a mechanism used to cancel previously authorized spending, to Capitol Hill to solidify some of DOGE’s cuts. A spokesperson for the Office of Management and Budget said the package will include $1.1 billion from the Corporation of Public Broadcasting, which funds NPR and PBS, and $8.3 billion in foreign assistance.

Musk’s criticism come as he steps back from his government work, rededicating himself to companies like the electric automaker Tesla and rocket manufacturer SpaceX. He’s also said he'll reduce his political spending, because “I think I’ve done enough.”

At times, he's seemed chastened by his experience working in government. Although he hoped that DOGE would generate $1 trillion in spending cuts, he's fallen far short of that target.

“The federal bureaucracy situation is much worse than I realized,” he told The Washington Post. “I thought there were problems, but it sure is an uphill battle trying to improve things in D.C., to say the least.”

Musk had previously been energized by the opportunity to reshape Washington. He wore campaign hats in the White House, held his own campaign rallies and talked about excessive spending as an existential crisis. He often tended to be effusive in his praise of Trump.

“The more I’ve gotten to know President Trump, the more I like the guy,” Musk said in February. “Frankly, I love him.”

Trump repaid the favor, describing Musk as “a truly great American.” When Tesla faced declining sales, he turned the White House driveway into a makeshift showroom to illustrate his support.

It’s unclear what, if any, impact that Musk's comments about the bill would have on the legislative debate. During the transition period, he helped whip up opposition to a spending measure as the country stood on the brink of a federal government shutdown.

His latest criticism could embolden Republicans who want bigger spending cuts. Republican Utah Sen. Mike Lee reposted a Fox News story about Musk's interview while also adding his own take on the measure, saying there was “still time to fix it.”

“The Senate version will be more aggressive,” Lee said. “It can, it must, and it will be. Or it won’t pass.”

Only two Republicans — Reps. Warren Davidson of Ohio and Thomas Massie of Kentucky — voted against the bill when the House took up the measure last week.

Davidson took note of Musk’s comments on social media.

“Hopefully, the Senate will succeed with the Big Beautiful Bill where the House missed the moment,” he wrote. “Don’t hope someone else will cut deficits someday, know it has been done this Congress.”

The Congressional Budget Office, in a preliminary estimate, said the tax provisions would increase federal deficits by $3.8 trillion over the decade, while the changes to Medicaid, food stamps and other services would reduce spending by slightly more than $1 trillion over the same period.

House Republican leaders say increased economic growth would allow the bill to be deficit neutral or reducing, but outside watchdogs are skeptical. The Committee for a Responsible Federal Budget estimates the bill would add $3 trillion to the debt, including interest, over the next decade.