Staff at the four recently closed Marks and Spencer stores have voted overwhelmingly in favour of industrial action.
180 people are losing their jobs with the closure of the sites in Dun Laoghaire, Tallaght, Mullingar and Naas.
The stores stopped trading on Saturday last August 17th, but the workers are still employed in clearing the locations.
Mandate says its members have voted by 88% in favour of placing pickets at the sites from September 10th.
John Douglas, the General Secretary of Mandate, is warning that the action could spread to other stores:
