While power returned to much of Manhattan and fuel supplies were headed for the disaster zone, residents of some of the hardest-hit areas faced a long wait for electricity and help after superstorm Sandy's devastating strike on the US Northeast.

With the US presidential election just three days away, at least 3.5 million homes and businesses remained without power in a region choked with storm debris and long gas lines reminiscent of the 1970s-era US fuel shortage. Angry residents wondered when their lives would return to normal.

President Barack Obama won early praise for the federal response to Sandy, which hammered the US northeast coast on Monday with 130-kph winds and a record surge of seawater that swamped homes in New Jersey and flooded streets and subway tunnels in New York City.

But continued television and newspaper images of upset storm victims could hurt the Democrat, who is locked in a virtual dead heat with Republican challenger Mitt Romney.

TV images might not be a problem in some of the worst-hit New York communities, like Broad Channel, Queens, which face waits of nine days or longer for electricity. Residents complain they are being ignored.

"We have nobody down here with video coverage," said Grace Lane, a grandmother who defied evacuation orders and rode out the storm in her second-story bedroom as water rushed through the first floor of her house.

Eight people - Lane, her husband, their two daughters, their husbands and her two grandchildren - are sleeping on air mattresses on the floor of the upstairs bedroom, the last usable room in the house. "At least my children are OK," she said.

Many houses were gutted by 1.5 metres of floodwater that raced through Broad Channel, where residents hauled broken furniture and soggy belongings out of their homes on Friday.

In a sign of security worries in the neighborhood, one garage full of debris stood open with a sign next to it reading: "LOOTERS WILL BE CRUCIFIED - GOD HELP YOU."

Moving to ease fuel shortages, the Obama administration directed the purchase of up to 45 million litres of unleaded fuel and 38 million litres of diesel, to be trucked to New York and New Jersey for distribution.

The government announced it would tap strategic reserves for diesel for emergency responders and waived rules that barred foreign-flagged ships from taking gas, diesel and other products from the Gulf of Mexico to Northeast ports.

The moves could help to quell anger triggered by growing lines - some of them miles long - at gas stations. Less than half of the stations in New York City, Long Island and New Jersey were operating on Friday.

New Jersey Governor Chris Christie ordered gas rationing in 12 counties to begin on Saturday under an "odd-even" system in which motorists with license plates ending in odd numbers would be able to buy gas on odd-numbered days.

"This system will ease the strain on those gas stations still operating while we work to bring more online," Christie said in a statement.

New York Mayor Michael Bloomberg also moved to tamp down rising anger in the most populous US city by dropping plans to hold the city's annual marathon. The city had been expecting more than 40,000 runners in Sunday's event.

Obama, who is back on the campaign trail after touring the disaster zone this week, planned to meet on Saturday morning with Homeland Security Secretary Janet Napolitano, Federal Emergency Management Agency Craig Fugate and others to discuss the storm response.

After the meeting, federal officials will travel to hard-hit areas including Manhattan, Breezy Point, Brooklyn, Long Island, Staten Island and cities in New Jersey to review response efforts.

The US death toll hit 102 on Friday after Sandy killed 69 people as a hurricane in the Caribbean. It struck the New Jersey coast on Monday as a rare hybrid superstorm after the hurricane merged with a powerful storm system in the north Atlantic.

Disaster modeling company Eqecat estimated Sandy caused up to $20 billion in insured losses and $50 billion in economic losses.

At the high end of the range, it would rank as the fourth costliest US catastrophe, behind Hurricane Katrina in 2005, the Sept. 11, 2001, attacks and Hurricane Andrew in 1992, according to the Insurance Information Institute.-Reuters