New York CNN — About 100 Starbucks stores across America will be on strike for the next three days, as the union attempts to turn up the pressure in its year-long battle with the coffee retailer. This is the second widespread strike by Starbucks Workers United, which staged a one-day strike in November on the day that Starbucks had its “red cup day” promotion, giving away reusable holiday cups. The union said it has so far won votes at 270 Starbucks stores. The union says this is a strike to protest unfair labor practices, including closing stores that have voted to join the union, such as the first store in the company’s Seattle hometown to vote for a union, and what the union says is the company’s refusal to bargain for an initial union contract. “They’re doubling down on their union-busting, so we’re doubling down, too,” said Michelle Eisen, a barista from the Buffalo store who was the first to vote for the union a year ago. “We’re demanding fair staffing, an end to store closures, and that Starbucks bargain with us in good faith.” Starbucks did not immediately respond to a request for comment. In the past it has defended store closings as being done in the name of employee safety. And it has blamed the union for the lack of progress at the bargaining table. The union has won about 80% of the union votes held so far. Despite its success, the 270 unionized stores are only a small fraction of the roughly 9,000 US company-owned stores that Starbucks operates. At the time of the previous strike Starbucks was able to keep many of the stores open by using managers and staff members from nearby stores.