Donald Trump is entering his second term with vows to cut a vast array of government services and a radical plan to do so. Rather than relying on his party’s control of Congress to trim the budget, Trump and his advisers intend to test an obscure legal theory holding that presidents have sweeping power to withhold funding from programs they dislike.

“We can simply choke off the money,” Trump said in a 2023 campaign video. “For 200 years under our system of government, it was undisputed that the president had the constitutional power to stop unnecessary spending.”

His plan, known as “impoundment,” threatens to provoke a major clash over the limits of the president’s control over the budget. The Constitution gives Congress the sole authority to appropriate the federal budget, while the role of the executive branch is to dole out the money effectively. But Trump and his advisers are asserting that a president can unilaterally ignore Congress’ spending decisions and “impound” funds if he opposes them or deems them wasteful.

Trump’s designs on the budget are part of his administration’s larger plan to consolidate as much power in the executive branch as possible. This month, he pressured the Senate to go into recess so he could appoint his cabinet without any oversight. (So far, Republicans who control the chamber have not agreed to do so.) His key advisers have spelled out plans to bring independent agencies, such as the Department of Justice, under political control.

If Trump were to assert a power to kill congressionally approved programs, it would almost certainly tee up a fight in the federal courts and Congress and, experts say, could fundamentally alter Congress’ bedrock power.

“It’s an effort to wrest the entire power of the purse away from Congress, and that is just not the constitutional design,” said Eloise Pasachoff, a Georgetown Law professor who has written about the federal budget and appropriations process. “The president doesn’t have the authority to go into the budget bit by bit and pull out the stuff he doesn’t like.”

Trump’s claim to have impoundment power contravenes a Nixon-era law that forbids presidents from blocking spending over policy disagreements as well as a string of federal court rulings that prevent presidents from refusing to spend money unless Congress grants them the flexibility.

In an op-ed published Wednesday, tech billionaire Elon Musk and former Republican presidential candidate Vivek Ramaswamy, who are overseeing the newly created, nongovernmental Department of Government Efficiency, wrote that they planned to slash federal spending and fire civil servants. Some of their efforts could offer Trump his first Supreme Court test of the post-Watergate Congressional Budget and Impoundment Control Act of 1974, which requires the president to spend the money Congress approves. The law allows exceptions, such as when the executive branch can achieve Congress’ goals by spending less, but not as a means for the president to kill programs he opposes.

Trump and his aides have been telegraphing his plans for a hostile takeover of the budgeting process for months. Trump has decried the 1974 law as “not a very good act” in his campaign video and said, “Bringing back impoundment will give us a crucial tool with which to obliterate the Deep State.”

Musk and Ramaswamy have seized that mantle, writing, “We believe the current Supreme Court would likely side with him on this question.”

The once-obscure debate over impoundment has come into vogue in MAGA circles thanks to veterans of Trump’s first administration who remain his close allies. Russell Vought, Trump’s former budget director, and Mark Paoletta, who served under Vought as the Office of Management and Budget general counsel, have worked to popularize the idea from the Trump-aligned think tank Vought founded, the Center for Renewing America.

On Friday, Trump announced he had picked Vought to lead OMB again. “Russ knows exactly how to dismantle the Deep State and end Weaponized Government, and he will help us return Self Governance to the People,” Trump said in a statement.

Vought was also a top architect of the controversial Project 2025. In private remarks to a gathering of MAGA luminaries uncovered by ProPublica, Vought boasted that he was assembling a “shadow” Office of Legal Counsel so that Trump is armed on day one with the legal rationalizations to realize his agenda.

“I don’t want President Trump having to lose a moment of time having fights in the Oval Office about whether something is legal or doable or moral,” Vought said.

Trump spokespeople and Vought did not respond to requests for comment.

The prospect of Trump seizing vast control over federal spending is not merely about reducing the size of the federal government, a long-standing conservative goal. It is also fueling new fears about his promises of vengeance.

A similar power grab led to his first impeachment. During his first term, Trump held up nearly $400 million in military aid to Ukraine while he pressured President Volodymyr Zelenskyy to open a corruption investigation into Joe Biden and his family. The U.S. Government Accountability Office later ruled his actions violated the Impoundment Control Act.

Pasachoff predicted that, when advantageous, the incoming Trump administration will attempt to achieve the goals of impoundment without picking such a high-profile fight.

Trump tested piecemeal ways beyond the Ukrainian arms imbroglio to withhold federal funding as a means to punish his perceived enemies, said Bobby Kogan, a former OMB adviser under Biden and the senior director of federal budget policy at the left-leaning think tank American Progress. After devastating wildfires in California and Washington, Trump delayed or refused to sign disaster declarations that would have unlocked federal relief aid because neither state had voted for him. He targeted so-called sanctuary cities by conditioning federal grants on local law enforcement’s willingness to cooperate with mass deportation efforts. The Biden administration eventually withdrew the policy.

Trump and his aides claim there is a long presidential history of impoundment dating back to Thomas Jefferson.

Most historical examples involve the military and cases where Congress had explicitly given presidents permission to use discretion, said Zachary Price, a professor at the University of California College of the Law, San Francisco. Jefferson, for example, decided not to spend money Congress had appropriated for gun boats — a decision the law, which appropriated money for “a number not exceeding fifteen gun boats” using “a sum not exceeding fifty thousand dollars,” authorized him to make.

President Richard Nixon took impoundment to a new extreme, wielding the concept to gut billions of dollars from programs he simply opposed, such as highway improvements, water treatment, drug rehabilitation and disaster relief for farmers. He faced overwhelming pushback both from Congress and in the courts. More than a half dozen federal judges and the Supreme Court ultimately ruled that the appropriations bills at issue did not give Nixon the flexibility to cut individual programs.

Vought and his allies argue the limits Congress placed in 1974 are unconstitutional, saying a clause in the Constitution obligating the president to “faithfully execute” the law also implies his power to forbid its enforcement. (Trump is fond of describing Article II, where this clause lives, as giving him “the right to do whatever I want as president.”)

The Supreme Court has never directly weighed in on whether impoundment is constitutional. But it threw water on that reasoning in an 1838 case, Kendall v. U.S., about a federal debt payment.

“To contend that the obligation imposed on the President to see the laws faithfully executed, implies a power to forbid their execution, is a novel construction of the constitution, and entirely inadmissible,” the justices wrote.

During his cutting spree, Nixon’s own Justice Department argued roughly the same.

“With respect to the suggestion that the President has a constitutional power to decline to spend appropriated funds,” William Rehnquist, the head of the Office of Legal Counsel whom Nixon later appointed to the Supreme Court, warned in a 1969 legal memo, “we must conclude that existence of such a broad power is supported by neither reason nor precedent.”