Northeast in crosshairs of possible 'superstorm' Sandy Photos: Sandy's destructive path NEW: Sandy responsible for at least 42 deaths (CNN) -- Sandy regained hurricane strength on Saturday, as weather forecasts predicted it would turn into a destructive "superstorm" that would impact the East Coast as early as Sunday. This storm, already responsible for at least 42 deaths in the Caribbean, will be studied for years to come, said Louis Uccellini, who is responsible for environmental prediction at the National Oceanic and Atmospheric Administration. CNN Weather estimates that damage from Hurricane Sandy could reach $3.2 billion. At least four states in its path and the nation's capital have declared states of emergency, and some airlines have announced they will allow passengers to change existing flights to and from Atlantic coast cities free of charge. Weather forecasters still predict it will push in a large storm surge as it nears land, inundate a broad, highly populated region with rain, and knock out power for perhaps weeks with destructive winds. Sandy was still predicted to merge with a strong cold front from the west and morph into a "superstorm." This "will energize this system, so we'll actually get an intensification of this system," Uccellini said. The resulting storm could sit over New England, creating serious trouble for millions of residents. Heavy snow was possible for the Appalachians. The tropical storm force winds were likely to spread over a vast distance, potentially up to 700 miles from North Carolina to Maine. That could mean widespread power outages, according to CNN's Weather Unit. Sandy has taken on a lopsided form and its heaviest winds should be in the northern and eastern sections of the storm as it nears land -- and be directed inbound toward the coastline. The surge is likely to hit during a full moon, when tides are the highest, worsening coastal damage. Computer models predict Delaware, Maryland and Virginia could see up to a foot of rain, according to the CNN Weather Unit. Isolated spots could see the worst rains in 500 years. At 8 a.m. ET Saturday, the National Weather Service said Sandy was about 335 miles south-southeast of Charleston, South Carolina. It was a Category 1 hurricane with winds of 75 mph. The U.S. target area was hard to predict. Some landfall computer models showed the storm striking somewhere between the border separating North Carolina and Virginia north to Connecticut. That area includes some of the most densely populated areas of the country. Sandy is responsible at least 29 deaths in Haiti, Civil Protection spokesman Joseph Edgard Celestin said. Four Haitians remained missing. Another 13 people were reported killed in Cuba, Jamaica and Puerto Rico. With early voting underway for the U.S. presidential election already under way in many states, Sandy's wrath could impact the political situation. In Virginia Beach, a campaign rally scheduled for Sunday for GOP nominee Mitt Romney was canceled because of the storm. There was no word on the status of other events scheduled later in the week. "We're keeping an eye on it," said a senior Romney campaign adviser. Similarly, Vice President Joe Biden canceled his visit to Virginia Beach on Saturday, "out of an abundance of caution to ensure that all local law enforcement and emergency management resources can stay focused on ensuring the safety of people who might be impacted by the storm," the Obama administration said. On Friday, Maryland Gov. Martin O'Malley left open the possibility that the vote could be rescheduled, or polling stations relocated inland. North Carolina issued states of emergency for 40 coastal counties. All the Northeast metro airports will experience delayed and canceled flights, the CNN Weather Unit said. American, United and Spirit airlines announced late Friday they would waive fees for passengers traveling in and out of many Atlantic coast cities who want to change plans. Washington's power company has ordered 2,500 additional linemen, 400 tree cutters and has staffed beefed up call center staff, according to affiliate WJLA. "We'll open up additional staging areas," PEPCO executive David Velazquez said. Late Friday, shoppers depleted pallets of mineral water stacked up outside a supermarket in Staten Island, New York. At 11 p.m. the parking lot was still full of people buying storm supplies, affiliate WABC reported. In New York City, workers covered subway ventilation grids to keep potential flood waters out. Bulldozers shored up sand to form barriers in hopes of preventing street flooding in coastal areas of the city's Burroughs. They did the same on New Jersey's shores as early as Thursday, CNN affiliate KYW reported. Residents in New Jersey have been stocking up on batteries and bottled water since Thursday, and hardware stores have put up preparedness displays, KYW reported. Farther south, in the Norfolk, Virginia, area, more than two dozen U.S. Navy ships were sent to sea to ride out the storm.