The company pressed for early negotiations aimed at winning concessions that it says are necessary to be competitive on a crucial bid for Coast Guard cutters early in the new year.

The 3,500 shipbuilders represented by Machinists Union Local S6 are casting their votes at the Augusta Civic Center.

If the tentative agreement is voted down, then there would be additional talks between the company and the union later in the new year. The existing contract doesn’t expire until May 22.

The proposal swaps pay raises for $2,500 bonuses in each year and includes modest increases in the company’s pension contributions. Workers would see some increases in health insurance deductibles and co-pays.

It also allows workers to perform additional tasks and allows limited use of subcontractors, but those provisions are scaled back from the company’s earlier proposals that drew the ire of workers.

Union President Jay Wadleigh said he has no idea whether shipbuilders will approve it.

Many shipbuilders say management, not shipyard workers, are to blame for any inefficiencies, and they resent the idea that they must bear the brunt of concessions to maintain future competitiveness.

The company initiated the early discussions last month because it wanted the changes before bidding on a contract for up to 25 Coast Guard offshore patrol cutters.

The shipyard’s 6,000-member workforce was warned that as many as 1,200 jobs could be cut if the yard fails to land the contract that spans two decades. Also bidding on the contract are Eastern Shipbuilding Group in Panama City, Florida, and Bollinger Shipyards in Lockport, Louisiana.

Bath Iron Works, a Navy shipbuilder, hasn’t built a ship for the Coast Guard since the 1930s. Bollinger beat Bath Iron Works in a competition for a smaller Coast Guard contract in 2008.