Unionized Starbucks employees in Seattle plan to hit the picket line Friday in a labor action expected to continue through Christmas Eve.

Amazon delivery drivers and Starbucks baristas are on strike in a handful of U.S. cities as they seek to exert pressure on the two major companies to recognize them as unionized employees or to meet demands for an inaugural labor contract.

Starbucks baristas went on strike at several stores in Chicago, Seattle and Los Angeles on Friday, with their union warning the walkouts could spread to hundreds of cafes by Christmas Eve if the coffee giant does not meet workers’ demands at the bargaining table.