Storm Sandy: US death toll close to 100
More than 90 deaths in the US have now been blamed on Sandy, the huge storm that has left residents on the east coast struggling to recover.
Worst hit were New York City and New Jersey, with fuel shortages the latest in a series of post-storm challenges.
Campaigning for Tuesday's presidential election - suspended earlier in the week - has fully resumed.
New York Mayor Michael Bloomberg endorsed President Barack Obama, citing his leadership on climate change.
Mr Bloomberg said Sandy could be evidence of climate change.
Of the two candidates, he said, "one sees climate change as an urgent problem that threatens our planet; one does not".
"I want our president to place scientific evidence and risk management above electoral politics."
Sandy arrived on the US Atlantic coast on Monday night, bringing hurricane-strength winds, flooding and blackouts.
About 4.5 million customers in 12 states are still without power.
The storm could cost the US $50bn (£31bn), according to forecasting firm Eqecat, which has doubled its previous estimate.
In New York, where Sandy brought a record 14ft (4.2m) tidal surge, the National Guard is to deliver a million meals and bottled water to residents affected by the storm.
In the south-western New York City borough of Staten Island, at least 15 bodies have been recovered.
The storm, one of the biggest to hit the US in decades, swamped the low-lying district with tidal surges, lifting whole houses off their foundations.
Anger is rising there at the delay in bringing aid.
One resident, Theresa Connor, told Reuters her neighbourhood had been "annihilated".
"They forgot about us... And Bloomberg said New York is fine. The marathon is on."
New York City councilman James Oddo said: "If they take one first responder from Staten Island to cover this marathon, I will scream."
Secretary of Homeland Security Janet Napolitano and Federal Emergency Management Agency (Fema) official Richard Serino will visit the borough on Friday.
Petrol station fights
Limited subway services returned to New York on Thursday, though four of the seven train tunnels under the East river remained flooded.
Fares on commuter trains, subways and buses have been temporarily waived in a bid to entice commuters off the traffic-choked roads.
Many of the petrol stations in the city and the state of New Jersey remained closed. Fights broke out amid long queues on forecourts.
Amtrak plans to restart its East Coast service - the busiest train line in the US - on Friday.
In Hoboken, New Jersey, across the Hudson River from New York City, some 20,000 people were still trapped in their homes as floodwaters slowly receded.
Officials warned residents not to walk in water polluted with sewage and chemicals.
Some 1.7 million people remain without power in the state, where the National Guard is helping with evacuations and meal distributions.
The cyclone also caused havoc further inland.
The state of West Virginia has seen up to 5ft of snow in some areas, after Sandy collided with two winter weather fronts.
The number of dead in the US now exceeds the toll from the Caribbean, where 69 people were killed by Sandy.