Negotiation delays with Albertsons – which owns Vons and Pavilions – and Ralphs are among the reasons for the vote. The impact of a work stoppage on online grocery delivery depends on the segment, Bishop said. "You've got the pure play coming from Amazon Fresh and then the online grocery that comes from your brick-and-mortar stores like Walmart Inc (NYSE: WMT ), Kroger Co (NYSE: KR ) and Safeway." Most of the order fulfillment occurs in-house, so if there is a strike companies that depend on store products will be disrupted. "And that's the fastest- growing portion of the business," Bishop said. Todd Walters, president of UFCW Local 135 in San Diego, said members who work in online fulfillment jobs at Vons and Ralphs fall under the general merchandise classification. Wages for that classification have fallen behind, he said, and the supermarket chains are stalling on a new contract. "Our members will tell the companies that we are frustrated," Walters said.