Top officials demanded answers from Columbia Gas after the company moved its deadline to restore service to customers in the Merrimack Valley by as much as a month.

“Columbia Gas needs to explain why, even after incorporating temporary repairs, it may take until mid-December to restore heat and hot water to families who have already faced these burdens for weeks and weeks,” Attorney General Maura Healey said in a statement. “We recognize this is a challenging recovery, but the new schedule is simply unacceptable. By November 19, Columbia Gas should provide all impacted residents with either temporary or permanent heat, or appropriate temporary housing, regardless of cost."

Yesterday, Columbia officials said they will be unable to completely restore service by Nov. 19, which the company had committed to last month. Instead, the company said all residents will have service between Dec. 2 and Dec. 16.

“Each day that goes past our deadline is a day too long. There have been obstacles we continue to see that have led to missed milestones,” said Joe Albanese, a consultant brought out to lead the recovery process for Columbia. “We understand the urgency you all have to return home and reopen your businesses.”

The Herald reported Wednesday Columbia’s pace was behind schedule, and officials have said for days Columbia’s efforts seemed to be too slow to hit the deadline.

Columbia’s progress in readying homes for gas service has fallen behind its own schedule. As of Wednesday, the company had cleared 829 homes out of nearly 8,000. That is short of their goal for Oct. 21 of 896. Columbia’s plan includes a steady increase in the number of homes cleared each day. Instead of replacing appliances in every home, Columbia workers will instead repair most gas appliances and come back after the winter to replace them.

The new timeline puts restoration after Thanksgiving, and at the edge of winter. Albanese said full gas restoration will now take place between Dec. 2 and Dec. 16.

“We are racing against the winter,” Albanese said.

In a joint statement, U.S. Sens. Edward J. Markey and Elizabeth Warren called on Columbia to do more to get residents back home quickly.

“Temperatures are dropping, and any delay in meeting its deadline means thousands of Merrimack Valley families and children will remain in jeopardy of freezing cold weather,” the statement said. “Columbia Gas should have known about and planned from the outset to address these obstacles.”