National Grid and union representatives have reached a tentative agreement after a bitter contract dispute left about 1,200 employees locked out for months in Massachusetts.

The utility and two United Steelworkers locals said in a joint statement Wednesday night that the terms of the agreement will be presented to union members by Jan. 7. It said details would not be released until members are able to vote.

This week, the governor signed legislation to extend unemployment benefits for employees who have been locked out since July.

There had been hope recently that a breakthrough might be in sight. National Grid also serves customers in Rhode Island and New York.