Environmentalists are making a last-ditch effort at the Supreme Court to stop the continued construction of parts of President Trump’s border wall.

The Sierra Club asked the justices to undo their decision from a year ago that allowed construction now that the U.S. Court of Appeals for the Ninth Circuit has ruled that the administration’s use of funds for the wall is unlawful.

Without the Supreme Court’s action, say lawyers for the American Civil Liberties Union, which is representing the Sierra Club and the Southern Border Communities Coalition, the Trump administration could simply run out the clock.

Court finds Trump border wall funding illegal

“The Trump administration has lost in every lower court, but is still rushing to complete the president’s border wall before the Supreme Court can review the merits of this case,” said Dror Ladin, an ACLU lawyer. “If the administration succeeds, there will be no border wall construction left to stop by the time the Supreme Court hears this case.”

A panel of the Ninth Circuit ruled last month that Trump’s transfer last year of $2.5 billion in military funds to pay for border wall construction was an illegal overreach of executive authority.

The president, who ran for office in 2016 promising that Mexico would pay for the border wall, has obtained more than $15 billion in U.S. federal funds for his signature project, including $5 billion provided by Congress through conventional appropriations. The president has tapped into Pentagon accounts for the remaining $10 billion, including the $2.5 billion transfer last year that the Ninth Circuit said was unlawful.

Last summer, the Supreme Court on a 5 to 4 vote allowed the administration to proceed with the transfers and contracts for construction even though House Democrats, affected states and environmental groups said that violated the will of Congress, which withheld the funds from the administration.

The fight over funding the wall led to a government shutdown.

Supreme Court says Trump funding of wall can proceed

But in allowing the administration last summer to proceed, the Supreme Court’s conservative majority said that the government had “made a sufficient showing at this stage” that private entities could not challenge the transfer of money by the executive branch.

Now, the Ninth Circuit panel in San Francisco agreed with a district judge who said that was not so. “It is for the courts to enforce Congress’s priorities,” the panel said in a 2 to 1 decision, and it found the Sierra Club “may invoke separation-of-powers constraints, like the Appropriations Clause, to challenge agency spending in excess of its delegated authority.”

The ACLU in its filing Wednesday said that the high court needs to step in now, or else it will be too late.

The administration has 150 days to appeal the Ninth Circuit’s decision, the ACLU petition says. Absent emergency action from the Supreme Court, “defendants will complete the entire wall before they even need to file a petition for certiorari with this court,” the petition states.