PITTSBURGH — The United Steelworkers union said Wednesday its members had voted to give it the authority to launch a nationwide strike against ArcelorMittal, the world's largest steel producer, if ongoing contract negotiations fail.

The union has been negotiating with Luxembourg-based ArcelorMittal since April over a new labor contract that would cover more than 14,000 workers and tens of thousands of retirees. The current contract expires Monday.

On Tuesday, the union distributed a notice to workers at 14 plants operated by ArcelorMittal saying there had been a "lack of progress" in the talks and asking for the authority to call a strike if the negotiations fail.

ArcelorMittal said it remains committed to working with the union to reach a settlement before Monday.

Workers at facilities in Indiana, Ohio, Pennsylvania, New York, South Carolina, West Virginia and Minnesota cast votes in meetings throughout the day, and a tally was expected Wednesday night, said Tony Montana, a USW spokesman participating in the talks.

Among the contentious issues are premiums for retiree health care, company contributions to a trust fund for health care, employee incentives, a profit sharing agreement and capital investments to improve aging facilities.