Sen. Bernie Sanders’ presidential campaign has been accused of sending operatives posing as culinary union representatives to gain access to workers in Las Vegas hotels, according to Ralston Reports.

The Sanders campaign did not return Ralston’s request for comment, but union officials said they had received reports from four hotels: The Rio, Paris, The Mirage and Planet Hollywood

“It’s inappropriate for any campaign to attempt to mislead Culinary Union members, especially at their place of work,” Yvanna Cancela, the culinary union Local 226’s political director, told Ralston Reports. “As of yet, the union has not made an endorsement, but is focused on a major citizenship and voter registration campaign while preparing for contract negotiations.”

According to the report, the Sanders campaign staffers were wearing yellow Local 226 pins so they could enter employee dining halls and talk to workers.