He was joined by Republican Governor Chris Christie as he met rescue workers and residents in Atlantic City, telling those affected: "We are here for you and we will not forget. We will follow up to make sure you get all the help you need until you rebuild."
Meanwhile, New York City's Bellevue Hospital last night evacuated 500 patients after back-up generators failed.
Sandy, a massive cyclone, killed at least 50 people across the north-eastern US, cutting power to millions.
New Jersey was directly in the storm's path on Monday night and part of the historic boardwalk washed away.
The president put campaigning on hold for a third day ahead of next Tuesday's US election, to direct the federal response to the storm but was due to resume campaigning today.
He and Gov Christie were given an aerial tour of the damage from the president's Marine One helicopter as towns and cities across the US East Coast took the first steps back to normality after being battered by Sandy. In all 61 people were killed in the US.
Two major airports reopened and the New York Stock Exchange came back to life, but the National Guard was still searching wrecked buildings in New Jersey for more survivors, or victims.
Last night British nationals were being issued with emergency passports to help them get home.
Danny Lopez, British Consul-General to New York, said consular staff were doing everything they could to help Britons stuck in the city and had issued emergency passports to 10 people already. Mr Lopez said: "JFK and Newark opened up. Currently both airports are not at full service but there are flights coming in and out."
AND he went on: "From a British perspective, the main problem we have are visitors who had to leave their hotels, due to the dangling crane on 57th Street.
"They haven't been able to return to get their poss-essions, which included in many cases their passports.
"What we have been dealing with are passengers who have come to the consul for emergency passports."
It was clear that restoring the region to its ordinarily frenetic pace could take days – and that rebuilding the hardest-hit communities and transportation networks could take considerably longer.
About 6.5 million homes and businesses were still without power, including 4m in New York and New Jersey. Electricity was out as far west as Wisconsin and as far south as the Carolinas.
The scale of the challenge could be seen in New Jersey, where National Guard troops arrived in the heavily flooded city of Hoboken to help evacuate thousands still stuck in their homes and deliver ready-to-eat meals. Live wires dangled in floodwaters that Mayor Dawn Zimmer said were mixing with sewage.
And new problems arose when firefighters were unable to reach blazes rekindled by natural gas leaks in the shore town of Mantoloking. More than a dozen homes were destroyed.
In New York City life was getting back to normal with morning rush-hour traffic heavy as people started returning to work and commuters queued for buses. On the Brooklyn Bridge, closed earlier because of high winds, joggers and cyclists made their way across before sunrise and car traffic on the bridge was busy.
AHUGE queue formed at the Empire State Building as the observation deck re-opened.
The Brooklyn-Battery Tunnel, connecting Brooklyn to Manhattan, and the Holland Tunnel, between New York and New Jersey, stayed shut.
But bridges into the city were open, and buses were free. Schools were closed for a third consecutive day in the city.
New York Mayor Michael Bloomberg said it could take four or five days before the subway, which suffered the worst damage in its 108-year history, is running again.
Flooding prevented inspectors from immed-iately assessing damage to key equipment.
Power companies said it could also be the weekend before electricity is restor-ed to Manhattan and Brooklyn, perhaps longer for other boroughs and the suburbs.
