Workers at the Trump Tower at City Center took to the picket line Thursday after going on strike over a labor dispute.

Doormen, porters, and maintenance and concierge workers are on strike because they say they haven't had a contract for the last six months. Many of the employees have worked at the building for close to a decade, but say their overtime hours are being contracted out to non-union staff.

Last week, the National Labor Relations Board filed federal charges against Trump Tower claiming that management has been unlawfully filming union workers on the picket line.

The workers were joined Thursday by several hundred members from the Service Employee International Union.