A massive ice storm blacked out homes from the Plains to the far Northeast, dealing a big “bah humbug” to thousands of families whose Christmas Eve was shaping up to be very cold and very dark.

Utility crews worked around the clock Tuesday to restore service to the more than half a million homes and businesses still without power since the deadly arctic blast slammed much of the country over the weekend. Some hardy revelers prepared to hunker down for the holiday, despite the lack of electricity, while others packed up their wrapped gifts and headed off to stay with family or friends.

The Potbury family was among nearly a quarter-million Michigan residents without power Tuesday. The family of four, of Mount Morris Township near Flint, lost electricity at 6 a.m. Sunday and has since stayed in a single bedroom warmed by generator-powered space heaters.

Lights on the Christmas tree of course were dark — one of several festive frustrations.

“Even though the house is freezing cold, the freezer items were starting to thaw out,” John Potbury said.

Jackson-based Consumers Energy, Michigan’s largest utility, said the storm was the worst for their customers during Christmas week in its 126-year history. More than 300,000 homes and businesses — nearly 17 percent of its 1.8 million electric customers — lost power during the storm that hit the state late Saturday. About 174,000 still were out Tuesday morning, and it could be days before power completely returns.

In the state capital, about 13,600 Lansing Board of Water & Light customers were waiting to have their electricity restored, while in the Detroit area about 55,000 DTE Energy customers still were without electricity.

Ted and Angela Montgomery, whose home was one of about 25,000 in Lapeer County that went dark, weren’t waiting around.

“We haven’t had any power in two days and DTE is saying it won’t be on until Dec. 27,” said Ted Montgomery, 61. “We planned a little family gathering we had to cancel.”

Montgomery said they had been using their fireplace to keep warm, but Tuesday they packed up their Chihuahua and African grey parrot and booked a hotel room near Detroit so they could spend the holiday with family in the area.

And the prospects of better weather were not very good. The National Weather Service said more snow was expected to move in to the Northern High Plains and Central Rockies on Tuesday before rolling into the Great Lakes and Midwest by this morning.

In Maine, the number of customers without power spiked to more than 100,000. Central Maine Power Co. said it had more than 1,000 people working on restoring power throughout the state.

Utilities in Vermont reported that about 6,800 homes still were without power. The Red Cross opened shelters in four communities, while the town of Barton opened its own shelter.

The nationwide death toll from the storm reached at least 12 on Tuesday, when a 50-year-old man was overcome by carbon monoxide fumes from a generator. It was the second reported death attributed to fumes from a generator during the storm.

Ken Fuller, who runs a generator repair shop in Lansing, Mich., said he typically closes by noon on Christmas Eve. At 12:30 p.m. he was cleaning out a carburetor with five more waiting to be serviced.

“The temperature outside is 15 to 20 degrees,” said Fuller, owner of Fuller’s Power Equipment Center. “Christmas is going to have to take second fiddle right now because houses are getting cold, freezing water pipes.”