PITTSBURGH » The United Steelworkers union has asked more than 14,000 members at facilities run by ArcelorMittal, the world's largest steelmaker, to allow it to call a strike if current contract negotiations fail. The labor union said in a notice distributed at 14 plants nationwide that a "lack of progress" in the talks, which began four months ago, prompted the strike authorization vote scheduled for today. The current contract is set to expire Sept. 1. ArcelorMittal operates in more than 60 countries. It has about 18,000 employees at 17 facilities in the U.S., including East Chicago, Burns Harbor and New Carlisle in Indiana.