A union representing Stop & Shop workers in Massachusetts has voted to authorize a strike after the employees’ contract expired at midnight.

United Food and Commercial Workers Local 1445 voted Sunday morning to authorize a potential strike during its meeting in Randolph. It is the first of five unions representing Stop & Shop workers in Massachusetts, Rhode Island and Connecticut to authorize a strike.

The remaining four are expected to follow suit, according to Local 1445 President Jeff Bollen.

The vote came just hours after employees’ three-year contracts expired at midnight. UFCW 1445 represents 10,000 Stop & Shop workers in Massachusetts.

Bollen said contract negotiations will continue over the next few weeks, but the vote gives the union the power to call a strike at any time. The union has asked members to keep working in the meantime.

“There’s a large percentage that we’re going to be going on strike this year,” Bollen said in a video posted to Facebook. “The company doesn’t seem to be backing off on things -- they are adamant about their proposals.”

Stop & Shop said in a statement that it will continue negotiations next week.

The grocery chain said it is one of the few remaining union grocers in New England and is forced to compete with non-union companies like Market Basket, Wegman’s and Trader Joe’s that have much lower labor costs.

“We look forward to having productive discussions with the unions next week and remain committed to reaching new agreements as quickly as possible,” the company said.