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.

The workers’ union hopes that adding employees at the Staten Island warehouse to a protest started by delivery drivers will increase pressure on Amazon.

Workers at an Amazon warehouse on Staten Island in New York will join thousands of others as the strike against the retail giant continues.