Bloomberg said the system worked well in New Jersey, where lines went from a two-hour wait to 45 minutes after Gov. Chris Christie announced a similar rationing plan.
Meanwhile, some who have been without power are demanding investigations of utilities they say aren't working fast enough. An angry New York Gov. Andrew Cuomo joined the calls for an investigation, ripping the utilities as unprepared and badly managed.
"Privately I have used language my daughters couldn't hear," he fumed. He added: "It's unacceptable the longer it goes on because the longer it goes on, people's suffering is worse."
The power companies have said they are dealing with damage unprecedented in its scope and doing the best they can. And there is no denying the magnitude of what they have done: At the peak, more than 8.5 million homes and businesses across 21 states lost power. As of Thursday, that was down to about 750,000, almost entirely in New York and New Jersey.
The nor'easter knocked out power to more than 200,000 customers in New York and New Jersey, erasing some of the progress made by utility crews.
"We lost power last week, just got it back for a day or two, and now we lost it again," said John Monticello of Point Pleasant Beach, New Jersey. "Every day it's the same now: Turn on the gas burner for heat. Instant coffee. Use the iPad to find out what's going on in the rest of the world."
New Jersey did not have a damage estimate of its own, but others have put Sandy's overall toll at up to $50 billion, making it the second-most expensive storm in US history, behind Hurricane Katrina, which swamped New Orleans in 2005.
Sandy killed more than 100 people in 10 states, with most of the dead in New York and New Jersey.
In a reminder of Katrina, the Federal Emergency Management Agency announced Thursday that it is moving manufactured housing into New York and New Jersey.
FEMA Administrator Craig Fugate said the disaster relief agency has several hundred mobile homes in its inventory of emergency supplies and has started moving some of them to disaster zone. He said it is unclear yet if FEMA will need to order more of the temporary homes.
Forty prefabricated homes were en route to a staging area in New Jersey, FEMA officials said. State officials in New Jersey and New York will decide where the houses will be placed, federal officials said.
More than 56,000 people have also been ruled eligible for FEMA's individual and households program, which provides money for renting a new place or housing repairs.
FEMA was widely criticized for using trailers after Hurricanes Katrina and Rita devastated New Orleans and parts of the Gulf Coast in 2005 after many of those trailers were later found to contain toxic levels of formaldehyde.
Fugate said the mobile homes being sent to New York and New Jersey have been approved by the Department of Housing and Urban Development. The mobile homes being used for this storm are not the same kind that were used after Katrina and Rita, FEMA said.
Defenders of the power industry, meanwhile, have pointed out that Sandy was huge and hit the nation's most densely populated corridor. By the Energy Department's reckoning, it left more people in the dark than any other storm in US history.
It did more than knock down power lines; it flooded switching stations and substations, forcing workers to take apart hundreds of intricate components, clean them, replace some of them, rewire others and put it all back together. Only after these stations are re-energized can workers go out and repair lines.
On Long Island, where more than 262,000 customers were without power and tempers were rising, Long Island Power Authority spokesman Mark Gross would not comment on the criticism, saying only that the utility is focused on restoring power.
Alfonso Quiroz, a spokesman for Con Ed, the chief utility in New York City, said: "I think we're going to be able to power through. Our objective was to get power restored to everyone by the weekend, and we're still working with that goal."
The Edison Electric Institute, the industry's main lobbying group, has called restoring power in Sandy's wake the "single biggest task the utility industry has ever faced." Brian Wolff, EEI senior vice president, said 67,000 utility workers from all around the country are on the job.
"An hour without power is too long. Power is an essential commodity. Our people get that. We are putting every resource to restoring power," he said. But he added, "This was not a minor event."
- AP