By Sunday morning, officials in Haiti said the storm was responsible for 65 deaths, as Sandy blew through the Bahamas and traveled north over the Atlantic Ocean, several hundred miles southeast of Charleston, S.C.
Two computer tracking systems remained in agreement that the hurricane would arrive on shore between the Delmarva Peninsula and Rhode Island. But Sandy’s reach will extend as far as 450 miles from its core, which prompted at least one governor, Chris Christie of New Jersey, to order evacuations of coastal areas and the state’s casinos.
The impending storm disrupted the rhythms of an otherwise warm fall weekend, as utility crews up and down the East Coast worked overtime to prepare, and hordes of anxious shoppers crowded into supermarkets and supply stores.
Even the presidential campaigns were touched. President Obama switched travel plans so he could leave Washington on Sunday before the storm begins and reach rallies in Florida and Ohio. Instead of hosting three events in Virginia on Sunday, Republican Mitt Romney’s campaign said the candidate would fly to Ohio.
Federal officials said that they expected the storm to create damaging flood and wind conditions across a vast and densely populated portion of the United States, from Virginia to New England, and as far west as the Great Lakes.
“We need to make sure people understand that this is going to go well inland,” Craig Fugate, the administrator for the Federal Emergency Management Agency, said in a conference call with reporters. “This is not a coastal threat alone.”
FEMA officials said they were uncertain which areas would be the most ravaged. The hurricane itself is expected to lose intensity before it merges with a separate storm system in the northeast.
Yet Sandy’s breadth makes its precise path almost irrelevant.
State and federal officials, Fugate said, are planning for several treacherous days throughout the Mid-Atlantic states, probably beginning Monday and perhaps extending to Thursday. Forecasters expect flash flooding from as much as 8 inches of rain. They are preparing for as much as two feet of snow in West Virginia, Virginia and North Carolina mountains.
In the Washington region, Jason Samenow, a meteorologist for The Washington Post’s Capital Weather Gang, predicted the worst of the storm to begin Monday, bringing as much as six inches of rain and causing wind gusts of as high as 60 mph.
D.C. Mayor Vincent C. Gray and the governors of Maryland and Virginia, as well as officials in several localities in the region, already have declared states of emergency.
In New Jersey, Christie announced mandatory evacuation of Atlantic City casinos and coastal barrier islands by 4 p.m. Sunday. He warned that power could be out for days.
“Everyone’s saying, ‘This . . . isn’t going to happen — the weathermen always get it wrong, so I’m just going to hang out here,’ ” Christie told reporters Saturday. “Please don’t, okay? We have to be prepared for the worst here.”
Amtrak began canceling some service. Beginning Sunday, some runs were to be canceled between Washington and New York, Miami and New York, and Chicago and Washington. Megabus said it would cancel runs between New York and Washington after 5 p.m. Sunday. Boltbus said it would cancel Monday and Tuesday service in the Northeast.
James Baker, the mayor of Wilmington, Del., issued an evacuation order for the southeastern section of his city, an edict that will require some 3,000 residents to clear out before the storm strikes.
In New York City, Mayor Michael Bloomberg advised residents and visitors to stay out of the parks. Construction sites also were ordered shut down.
Across the Washington region, people crowded into supermarkets and hardware stores, loading up on food and supplies, if there were any to be found.
Customers took up to a half hour to find parking on Saturday at the Georgetown Safeway, where bottled water was gone by late afternoon and two shoppers argued over the last box of elbow pasta.
At Target in Columbia Heights, flashlights were gone by Saturday morning. Sales of gasoline were up 20 percent at an Exxon station on Wilson Boulevard in Virginia, where the manager called the supplier to order more. “People are worried,” said Dharmendra Tanna, the assistant manager. “We have not seen anything like this.”
“Everyone has freaked out. Wow,” said Jennifer Gaskins, 59, as she gaped at the bare hooks where the flashlights would have hung.
In the District, social services workers tried to warn homeless people and tell them that the city would keep shelters open around the clock beginning Monday.
“We’ll keep them open all day long for the duration of the hurricane and the aftermath,” said David A. Berns, director of the District’s Department of Human Services. “Otherwise, the homeless adults would be on the street.”
Public utility crews were preparing.Pepco, the power company for the District and suburban Maryland that has been criticized for poor reliability, warned customers of the possibility of long periods without electricity.
Company officials predicted that trees still thick with leaves could collapse under the rain and wind, falling on lines, snapping poles and bringing down wires.
Pepco has asked for additional utility workers from 2,900 to 3,600.The Baltimore Gas and Electric Co. said it had asked for 2,000 out-of-state utility workers, and the first 1,300 were to begin arriving at Baltimore-Washington International Marshall Airport Sunday.
BGE sent out automated phone calls urging customers to have a plan in place to protect their families and property.
Joe Stephens, Howard Schneider, Rebecca Cohen, Ashley Halsey, Martin Weil and Caitlin Gibson contributed to this report.