Members of United Food & Commercial Workers Local 400, which represents more than 2,000 employees of stores in northern Virginia and in Maryland south of Baltimore, filed the case last week with the National Labor Relations Board.
"Shoppers management is trying to ram pay and benefit cuts down our throats while forcing us to keep our mouths shut about it," Christy Bennett, a Shoppers worker and member of Local 400's bargaining advisory committee, said in an announcement of the NLRB case.
The current collective bargaining agreement, which also covers workers at Baltimore-area stores, expires July 7.
Steve Sylven, a spokesman for Shoppers, said the NLRB case allegations were "without merit."
"We are committed to working with the union to reach a fair agreement that continues to provide our associates with good wages, access to affordable health care and secure retirement benefits," Sylvan said in an emailed statement. "Shoppers respects the rights of our associates to express their opinions and acts in accordance with all applicable labor laws."