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Attorneys for the Trump administration made an emergency request to the Supreme Court on Tuesday night to stop it from having to release billions of dollars in foreign aid spending Congress has already earmarked. It’s the latest turn in a long-running legal fight over foreign assistance that heads back to the high court for the second time in six months.

The money at stake in the case, nearly $12 billion, is a pot of funds set aside for the U.S. Agency for International Development (USAID) that Congress says must be obligated before the fiscal year ends on September 30. The Trump administration, moving fast after the president’s return to the White House in January, had an executive order issued on the president’s first day in office that directed all federal agencies to stop disbursing foreign aid funds, nearly all of them.

Trump said the move was part of a push to root out “waste, fraud, and abuse” in U.S. foreign spending. The order was challenged immediately in court, and in February, U.S. District Judge Amir Ali in Washington, D.C., blocked the administration from withholding the money. In his order, Judge Ali said the White House must continue to release money for projects Congress had already signed off on. Ali’s ruling set a schedule for the Trump administration to start paying out on billions of dollars in USAID grants.

Trump officials weren’t done fighting the move. The U.S. Court of Appeals for the D.C. Circuit revisited the case at the start of the month and voted 2-1 to lift Judge Ali’s injunction. In her ruling for the majority, Judge Karen L. Henderson, an appointee of President George H.W. Bush, said the plaintiffs in the case, foreign aid groups that are trying to restore their grant payments, did not have the right to sue the administration. Henderson wrote that the groups had no legal “cause of action” under what’s called the doctrine of impoundment.

The appeals court ruling was a big victory for Trump, but there’s a wrinkle to it. The court has not formally issued a mandate for the ruling. Because of that, Judge Ali’s earlier order and the payment schedule the judge laid out remain in effect. The administration is now working against the clock to avoid a scenario in which it must fork over the entire $12 billion before the fiscal year runs out on September 30.

Trump lawyers are moving full steam ahead, fast-tracking the appeal all the way to the Supreme Court with an emergency filing on Tuesday. In that filing, U.S. Solicitor General D. John Sauer wrote that unless the Supreme Court acts, the government “will be required to rapidly obligate” some $12 billion in foreign aid funds before the end of September. As with his earlier filing, Sauer argued that the case should not be decided by federal courts.

“Congress did not upset the delicate interbranch balance by allowing for unlimited, unconstrained private suits,” Sauer wrote in the filing. He also noted that “any lingering dispute about the proper disposition of funds that the President seeks to rescind shortly before they expire should be left to the political branches, not effectively prejudged by the district court.”

The argument is the opposite of what the plaintiffs in the case are arguing. The plaintiffs, a group of foreign aid groups whose work is supported by USAID, are saying Congress already approved the funds, and the president cannot unilaterally block them. The ICA, the law passed in the 1970s to rein in executive discretion over federal spending, is the most important law cited by both sides. The plaintiffs in the case also point to the Administrative Procedure Act. The ICA and APA are the main statutory authorities that the plaintiffs are arguing in favor of their case.

Legal experts have also suggested other important implications of the case beyond simply whether or not Trump can block the aid payment. Trump’s lawyers have pushed a theory of the case that could have given a president a lot more discretion over how to spend congressionally approved money. The administration ultimately lost at the Supreme Court in the case earlier this year by a 5-4 vote, but the fight is back in the justices’ hands now.

For the Trump administration, the case is part of a larger effort to transform U.S. spending priorities and take a harder line on international aid. For the aid groups, the case is a fight over survival: If they do not get the money they were promised, they have projects already in the field all over the world that they have to cut back or possibly shutter.

The appeals court decision is currently in partial limbo, and the administration is pressing the Supreme Court to rule on the case with as much urgency as possible. How the justices handle this emergency appeal could have a huge effect on the fate of not just $12 billion in foreign aid, but the administration’s approach to it.