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Lawyers for the Trump administration on Tuesday night asked the Supreme Court to allow the federal government to block billions of dollars in foreign aid spending that Congress had previously appropriated, sending the fight over U.S. Agency for International Development (USAID) funding back to the high court for the second time in six months.

The dispute centers on nearly $12 billion in foreign aid that Congress had previously set aside for USAID and that must be spent by September 30, when the fiscal year comes to an end. In January, after President Donald Trump returned to office, he signed an executive order on his first day back in the White House, instructing the federal government to essentially stop all foreign aid disbursements. The president said the move was part of an overall effort to root out “waste, fraud, and abuse” in foreign spending.

The order was quickly challenged in court, and in February, U.S. District Judge Amir Ali in Washington, D.C. blocked the effort. In a ruling, Judge Ali said that the White House was required to continue to disburse money that Congress had already approved to be spent. In effect, Judge Ali required the Trump administration to restart payments on billions of dollars in USAID grants.

The Trump administration appealed, however. The U.S. Court of Appeals for the D.C. Circuit revisited the case at the beginning of the month. In a 2-1 ruling, the court vacated Judge Ali’s injunction. Judge Karen L. Henderson, a George H.W. Bush appointee, wrote for the majority, saying that the plaintiffs in the case, foreign aid groups that want the government to start releasing their grant payments, did not have a legal basis to sue the administration in the first place. Henderson wrote that the group did not have a proper “cause of action” under a doctrine known as the doctrine of impoundment.

The ruling from the appeals court is a major win for Trump, but it has not yet issued a so-called mandate formalizing its ruling. That means that Judge Ali’s order and the payment schedule that he set out in his ruling remain in effect. As a result, the Trump administration is in a race against time to avoid being forced to pay out the full $12 billion before the fiscal year deadline on September 30.

Win or lose, the case could have major implications for Trump and his policies. The Justice Department’s filing on Tuesday, which was authored by U.S. Solicitor General D. John Sauer, says that unless the Supreme Court intervenes, the government will be required to “rapidly obligate some $12 billion in foreign-aid funds” by the end of September. The Justice Department said that the decision on how to handle the payments is not for the federal courts to decide, but that the matter should be left to the political branches of the government.

“Congress did not upset the delicate interbranch balance by allowing for unlimited, unconstrained private suits,” Sauer wrote in his filing to the high court on Tuesday. He continued, adding 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 plaintiffs in the case, a group of foreign aid organizations that have projects that rely on USAID spending, are arguing the exact opposite. The groups have argued that the president lacks the power to block money that Congress has already appropriated for foreign spending. The plaintiffs, the groups challenging the administration in the case, are citing the Impoundment Control Act (ICA), which was passed in the 1970s as a check on the executive branch, and the Administrative Procedure Act as the statutory bases for their claims against the administration.

The dispute has taken on significant political overtones with a range of legal implications. On the one hand, a win for the administration would further bolster the president’s ability to rescind or delay spending after Congress has already appropriated money. But if the plaintiffs win, it could serve to further limit the executive branch’s discretion in the budget process.

The Supreme Court has already weighed in on the question once, delivering a narrow 5-4 decision earlier this year. But with the deadline looming, and billions of dollars at stake, the Trump administration is asking the justices to break up the logjam once again.

The case is part of Trump’s broader push to both change spending priorities in the U.S. and gain more control over foreign assistance programs. For aid groups, the dispute is existential. Projects already underway across the globe could be affected or even closed if they do not receive the funds as they had expected.