A labor union and public-interest legal groups sued the Trump administration on Friday for inserting partisan language into federal employees’ out-of-office replies during the government shutdown.

The American Federation of Government Employees, which represents some 800,000 federal workers, also sent a cease-and-desist letter to the administration demanding it put an end to the political messaging in workers’ autoreplies at the Education Department.

“Federal employees already are suffering financially by going without a salary,” Everett Kelley, the union’s president, said in a statement. “Now the administration has directly and deliberately violated the First Amendment rights of furloughed workers.”

After government funding lapsed, furloughed workers across the federal government were instructed, per usual, to set up out-of-office replies during the shutdown. But last Thursday, employees inside the Education Department realized their nonpartisan replies had been altered so that the messages blamed Democrats for the funding lapse, an agency worker confirmed to HuffPost.

Workers did not consent to having their replies changed to the new partisan language, which was first reported by NBC News. Many felt they were being used to violate the Hatch Act, which limits political activities by federal employees.