The legal battle over Trump's federal funding freeze is just beginning

WASHINGTON (AP) — The Trump administration's push for a sweeping pause on federal grants and loans totaling potentially trillions of dollars is on hold for now, on the order of a federal judge.

But the legal battle over the plan that set off panic and confusion across the country is just beginning, and it could become a constitutional clash over control of taxpayer money and expansion of executive power before the Supreme Court.

Here's a look at the legal issues at play:

The power of the purse

The Constitution gives Congress control over federal spending, a setup key to the framers' vision of separating major powers between branches of government.

Once appropriations are approved, the White House has the job of doling out money to states, agencies and nonprofits through the Office of Management and Budget.

Typically, the White House sends out money according to the priorities laid out in Congress, though there have been times when presidents have refused to spend all the cash they get. Thomas Jefferson, for example, declined to use money set aside for gunboats in the early 1800s.

When the president won't spend money that Congress has set aside, it's called impoundment.

Trump's Republican administration has framed the halt to federal grants and loans as a brief pause that would allow for an across-the-board review to align spending with his ideological agenda, rather than an impoundment.

What does the law say?

A showdown between Congress and President Richard Nixon in the 1970s led to a law laying out specific rules around impoundment.

Nixon had tried to halt billions of dollars in federal funding for things ranging from social programs to water treatment. The administration faced a wave of lawsuits that it overwhelmingly lost, said William Ford, a policy analyst at the nonpartisan group Protect Democracy.

Congress also passed the Impoundment Control Act in response. The act says that if there's a delay in sending out federal money, the White House is supposed to tell Congress about the pause and how much money is involved. There are some exceptions for logistical issues related to specific programs.

The law also says any longer-term freeze has to get congressional approval. While duels over spending have continued since then, the law has rarely been invoked, Ford said.

The issue could head to the Supreme Court

Trump allies have suggested in the past that the Impoundment Control Act is unconstitutional, arguing the White House should have more control over spending.

The clash could end with the administration pursuing specific funding cuts, or it could end up challenging before the conservative-majority Supreme Court, said John Yoo, a Berkeley Law professor who served in the George W. Bush administration.

The justices weighed in on the Nixon funding fight in a case known as Train v. New York. The court unanimously found that the president couldn’t block sewage treatment funding that had already been approved by Congress.

What else might happen next?

The White House has said that the funding freeze wouldn’t affect programs that send money to individual people, like Social Security, Medicare, food stamps, student loans and scholarships.

It could still affect trillions of dollars and cause widespread disruption in a wide range of programs, from the National Science Foundation to Meals on Wheels.

It's also set off at least two lawsuits, one helmed by the group Democracy Forward representing nonprofits that get federal funding and another from nearly two dozen Democratic states.

They say the pause is clearly unconstitutional and breaks federal contracting law. The nonprofits say ideological bent of the proposed review also violates their freedom of speech.

The temporary stay issued by U.S. District Judge Loren L. AliKhan in Washington lasts until Feb. 3, when she'll consider whether to extend the block or let the plan go forward.