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.

Workers at an Amazon warehouse in San Francisco are on strike Thursday, joining six other delivery stations of the e-commerce company across the country. The Teamsters, who are seeking a labor agreement during a key shopping period,

Coordinated strikes ahead of Christmas in a handful of cities including San Francisco and New York see the Teamsters challenge the nation’s second-largest private employer.