The U.S. Department of Justice on Tuesday requested a stay of proceedings in its legal fight with US Airways Group Inc (LCC.N) and American Airlines parent AMR Corp (AAMRQ.PK) over the carriers’ proposed merger, citing the federal government shutdown.

“Absent an appropriation, the Department of Justice attorneys and employees are generally prohibited from working, even on a voluntary basis,” the Justice Department said in a motion.

“This is creating difficulties for the Department to perform the functions necessary to support its litigation efforts,” the department added.

The filing stated that lawyers for the airlines object to the stay request.

The Justice Department and several states sued on August 13 to stop the merger, arguing that the deal to create the world’s biggest carrier would lead to higher fares and stifle competition. A federal judge was scheduled to hear the case without a jury beginning November 25.

Shares of US Airways were up 1.7 percent to $19.28 on Tuesday, while AMR was up about 2 percent to $4.20