ArcelorMittal workers voted overwhelmingly to authorize a strike in mid-September, but the two sides returned to the bargaining table.

The union takes credit for the turnaround of the U.S. domestic industry, partly by forgoing raises for the last three years while steelmakers were struggling and losing money. Steelworker pay has risen only 4.5 percent since 2012 as compared to 15 percent for other private section workers, according to the Bureau of Labor Statistics. It's also failed to keep pace with the 8 percent inflation over that period.

"Our health care plans already require co-pays on medical and prescription drug coverage, deductibles and cost sharing with ArcelorMittal," McCall and Millsap wrote. "We are not abusers of health care — it is, in fact, a part of our compensation. We deserve it and have earned it, and we should not have to fight about keeping health care every time we enter into negotiations. Not only is our health care being attacked, but the promise and commitment for our retiree health care is under constant assault by ArcelorMittal."