(CNN) - The Justice Department, citing the partial government shutdown, is asking a judge to put on hold a lawsuit brought by three Democratic senators who are challenging President Donald Trump's appointment of acting Attorney General Matthew Whitaker.
The filing is the latest indication of how the shutdown is impacting government operations.
The case is brought by Sens. Richard Blumenthal of Connecticut, Sheldon Whitehouse of Rhode Island and Mazie Hirono of Hawaii. They argue Whitaker's appointment violates the Appointments Clause of the Constitution.
In the motion, filed with the US District Court for the District of Columbia, Assistant Attorney General Joseph Hunt says the department is unable to respond to the complaint "until Congress has restored appropriations to the Department." He added that the government does not know when funding will be restored by Congress.
"We greatly regret any disruption," he said.
The Justice Department has defended Whitaker's appointment, concluding that it was legally justified under the Vacancies Reform Act because it's a temporary appointment and "he had been serving in the Department of Justice at a sufficiently senior pay level for over a year." He had previously served as Sessions' chief of staff.
The Senate Democrats' lawsuit, however, argues that his appointment is unconstitutional under the Constitution's Appointments Clause requiring Senate confirmation of high-level federal appointees.
Trump has nominated William Barr to take over the Justice Department on a permanent basis.