Obama will visit ravaged New Jersey on Wednesday, where search and rescue missions have become a priority.
A berm in Bergen County, N.J., was breached this morning, resulting in four to five feet of water flowing into three towns and endangering as many as 2,000 people, said Jeanne Beratta, spokeswoman for the Bergen County Office of Emergency Management.
"We're doing rescues by boat. We're doing rescues with large trucks. We're doing rescues all over those areas," Baratta told "Good Morning America." "It's going to continue all day because now we're just search and rescue."
New Jersey Gov. Chris Christie said that the state "kind of took it in the neck worse than any other place," but praised Obama and his administration for how it has handled the crisis.
"[Obama] called me last night around midnight to ask what else can be done," Christie told "GMA." "I have to say, the administration, the president himself and FEMA administrator Craig Fugate have been outstanding with us so far. We have a great partnership with them and I want to thank the president personally for his personal attention to this."
Other parts of the country were struggling with snow and blizzard conditions. West Virginia was under a blizzard warning and more than two feet of snow was reported in some parts of the states. More than 100,000 customers are without power.
Sandy also brought winter conditions from North Carolina to Pennsylvania, and into Ohio.
The former hurricane had joined forces with a cold front coming from the northwest and a high pressure system from Greenland to dump snow on eight states. Davis, W.Va., has been blanketed with 17 inches of snow, which continued to fall into the early morning.
By Thursday, meteorologists predict up to three feet of snow was possible in higher elevations.
New York University Medical Center was among the millions left without power in the wake of Sandy. A full evacuation was under way after the hospital's back-up generators had failed.
Early this morning, approximately 200 patients had been evacuated by private ambulance with assistance from the FDNY.
John Miksad, senior vice president for electric operations at Con Edison, said it was too soon to say when power could be restored and that inspectors would be out once it was daylight to assess the damage.
Sandy was downgraded from a hurricane to a post-tropical storm shortly before it made landfall at 8 p.m. in Atlantic City, N.J., on Monday.
By late Tuesday evening, Sandy remained a tropical cyclone with maximum sustained winds of 40 mph. Though it was weakening over Pennsylvania, it churned up the waters of the Great Lakes, prompting gale warnings and small craft advisories in some locations, according to the National Weather Service. Parts of the mid-Atlantic and Northeast states remained under flash flood watches and warnings.
"Sandy is expected to turn north across Western New York or Lake Erie ... and continue to move northward into Canada on Wednesday," the National Weather Service said in it's 11 p.m. ET briefing Tuesday.
ABC News' Max Golembo, Richard Esposito, Russell Goldman, Michael S. James, Genevieve Shaw Brown, Molly Hunter and Serena Marshall contributed to this report.