Workers leave Bath Iron Works after a shift in this April 3, 2020, file photo. Credit: Robert F. Bukaty | AP

Bath Iron Works is heading into a week of uncertainty after a union negotiating team rejected the shipbuilder’s final offer. Workers will begin voting on the three-year contract on Thursday.

After the company issued its final offer Saturday, Machinists Union Local S6, which represents more than 4,000 workers, announced that its negotiating team “unanimously rejects the last best and final contract.”

The proposal would give shipbuilders a 3 percent raise during each year, with wages for a “first-class mechanic” growing from $25.80 per hour to $28.19 per hour by the third year, in addition to a $1,200 signing bonus, the company said.

The company would keep intact company 401(k) matching contributions and would raise pension contributions by a small amount. But it would require the workers to contribute larger co-pays for health insurance.

One of the biggest sticking points is the hiring of subcontractors, which has angered shipbuilders. The company has hired 1,500 workers over the past year but contends contractors are needed to get caught up. The company is currently six months behind schedule.

The current contract expires at midnight on June 21. The company and union will be educating workers about the contract ahead of voting that begins Friday and wraps up at noon on Sunday.

Local S6 is the largest union at the company, representing 4,300 workers. The shipyard builds destroyers for the U.S. Navy.