The Trump administration is looking for funds to redirect towards the construction of a southern border wall, representatives said over the weekend.

“Presidents have authority to defend the nation,” acting White House chief of staff Mick Mulvaney told CNN on Sunday on whether President Trump could use emergency powers to build the wall in the name of national security.

“The president has asked every single Cabinet secretary, and the Office of Management and Budget, to go out and find money that can be used legally to guard the southern border,” said Mulvaney, who currently runs OMB as well.

“I’m actually heavily involved with it and have been working with all the Cabinet secretaries to try and find money that we can legally use to defend the southern border,” he said.

The federal government is on the seventeenth day of a partial shutdown after negotiations between Republicans and Democrats broke down just before Christmas over border wall funding. President Trump has asked for $5 billion in the next spending bill to fund the wall while Democrats have refused to approve anything over $1.6 billion for border security.

The president previously said he could use his national emergency powers to begin construction on the barrier. He has floated using the military to build it.

White House press secretary Sarah Sanders confirmed that Trump is looking at other options apart from congressional approval to fund the barrier with Mexico, one of his core campaign promises.

The White House is “exploring every option available that the president has,” Sanders told Fox News on Sunday. “Whatever action he takes will certainly be lawful.”

Sanders added that the president is not “holding anybody hostage” by refusing to sign spending legislation that would fund the other shut down sections of government besides Homeland Security.

“He knows it’s better if they can focus on getting all these packages done at once,” she said.