Workers at a Nissan Motor Co. NSANY, +0.27% assembly plant in Mississippi have voted against forming a union, the Associated Press reported, another blow to a United Auto Workers hoping to organize the foreign-owned auto plants in the American South. Representatives of Nissan and the UAW said late Friday that 2,244 workers, or 62%, voted against the UAW, while 1,307, or 38%, favored unionizing. The union filed seven new charges with the National Labor Relations Board just before polls closed Friday, alleging that Nissan had broken federal labor laws during the campaign, the AP reported. If the labor board rules in favor of the charges, the board could order a fresh election.