US President Barack Obama (C) shake hands with workers after a briefing on huricane Sandy at FEMA Headquarters in Washington, DC, USA, 28 October 2012. [CFP]

Earlier on Sunday, Obama declared a state of emergency for Maryland, making federal aid available for local response.

Several northeastern states, including Maryland, Virginia and New Jersey, have already declared state of emergency by themselves since Friday in preparation for the approaching Hurricane Sandy.

Speaking on CNN's State of Union on Sunday, Virginia Governor Bob McDonnell said the state had learned lessons from the last storm which left many local residents without power for days, and already got about 2,000 additional people this time to help with the state's power supply.

He also said the state Board of Election was already planning for extended hours in advance for absentee voting as the hurricane may potentially prevent voters getting out to cast ballots on Election Day.

The Virginia National Guard was authorized to call up to 300 personnel on state active duty for possible severe weather recovery operations from Hurricane Sandy.

In New Jersey, where Hurricane Sandy most likely makes landfall, Governor Chris Christie ordered a mandatory evacuation of the state's barrier islands, including the casino center Atlantic City, as well as the shutdown of 12 casinos by Sunday afternoon.

New York City also announced the closings of its mass transit and school systems and ordered residents to leave some low-lying areas on Sunday.

Airlines have canceled hundreds of flights into airports along the US east coast ahead of the arrival of a major storm, hundreds of domestic flights have been called off. Some international flights into New York and Washington were also canceled on Monday.