Mulvaney said that while President Trump doesn't want it to happen again, he perceives national security to be his No. 1 priority he is refusing to back down from his demands for funding to build a border wall.
"I'm not in a position to say the president will absolutely sign or will not sign. Here's what we do know. The president has to sign a piece of legislation in order to keep the government open," Mulvaney said.
"He cannot sign anything that they put in front of him. Excuse me. He cannot sign everything they put in front of him. There'll be some things that simply we couldn't agree too, so the government shutdown is technically still on the table. We do not want it to come to that, but, that option is still open to the president and will remain so," he said.
The government will run out of money again if lawmakers do not cut a deal on border security funding by Friday.