Trump's joint statement with Vice President-elect JD Vance, which stopped the bill in its tracks, punctuated a daylong torrent of social media posts by Musk attacking the budget legislation as full of excessive spending.

"Kill the Bill!" Musk wrote on his social media platform X as he dangled primary challenges against anyone who voted for the budget deal, a threat Trump later echoed in a post of his own.

The episode showcased the growing political influence of Musk, whom Trump has selected alongside entrepreneur Vivek Ramaswamy to spearhead the Department of Government Efficiency, a nongovernmental task force formed to find ways to fire federal workers, cut programs and slash federal regulations. Musk, the world's richest man, spent around $200 million to support Trump's candidacy this year.

In his statement with Vance, Trump criticized the bill and advocated for extending the debt ceiling with President Joe Biden in office.

"Increasing the debt ceiling is not great but we'd rather do it on Biden's watch. If Democrats won't cooperate on a debt ceiling increase now, what makes anyone think they would do it in June during our administration? Let's have this debate over the debt ceiling now."

Trump's opposition to what was considered must-pass legislation reinjected a sense of chaos and political brinkmanship that was reminiscent of his first term in office. It was a dramatic turn of events for House Speaker Mike Johnson, who negotiated the bill and has been undermined by Trump as he faces reelection for his post in just a couple of weeks. Republicans have a slim majority, raising the possibility of a replay of leadership disputes that paralyzed the House a year ago.

Grover Norquist, president of Americans for Tax Reform and a veteran of Washington's budget battles, was concerned about the lack of a clear plan as a potential government shutdown approached.

"There's got to be a second part of the strategy," he said.

But others were thrilled by Musk's involvement.

"In five years in Congress, I've been awaiting a fundamental change in the dynamic," posted Rep. Dan Bishop, a Republican from North Carolina. "It has arrived."

Musk began criticizing the measure as soon as it was released Tuesday evening, and he continuously posted about it Wednesday.

"Stop the steal of your tax dollars!" he wrote. He also called it "one of the worst bills every written."

Sometimes he amplified false claims, such as the idea that the legislation included $3 billion for a new football stadium in Washington. In reality, the legislation would transfer ownership of the land from the federal government to the city, paving the way for eventual development.

Musk appeared emboldened by the experience.

"The voice of the people was heard," Musk wrote. "This was a good day for America."

Democratic House leader Hakeem Jeffries warned Republicans, "You break the bipartisan agreement, you own the consequences that follow."