Forget distinctions like tropical storm or hurricane. Don't get fixated on a particular track. Wherever it hits, the rare behemoth storm inexorably gathering in the eastern U.S. will afflict a third of the country with sheets of rain, high winds and heavy snow, say officials who warned millions in coastal areas to get out of the way.

"We're looking at impact of greater than 50 to 60 million people," said Louis Uccellini, head of environmental prediction for the National Oceanic and Atmospheric Administration.

As Hurricane Sandy barreled north from the Caribbean — where it left nearly five dozen dead — to meet two other powerful winter storms, experts said it didn't matter how strong the storm was when it hit land: The rare hybrid storm that follows will cause havoc over 800 miles from the East Coast to the Great Lakes.

"This is not a coastal threat alone," said Craig Fugate, director of the Federal Emergency Management Agency. "This is a very large area."

President Barack Obama was monitoring the storm and working with state and locals governments to make sure they get the resources needed to prepare, administration officials said.

New Jersey Gov. Chris Christie declared a state of emergency Saturday as hundreds of coastal residents started moving inland and the state was set to close its casinos. New York's governor was considering shutting down the subways to avoid flooding and half a dozen states warned residents to prepare for several days of lost power.

Sandy weakened briefly to a tropical storm early Saturday but was soon back up to Category 1 strength, packing 75 mph winds about 305 miles south-southeast of Cape Hatteras, N.C., as of 11 p.m. Forecasters said the storm was spreading tropical storm conditions across the coastline of North Carolina, and they were expected to move up the mid-Atlantic coastline late Sunday. Experts said the storm was most likely to hit the southern New Jersey coastline by late Monday or early Tuesday.

Governors from North Carolina, where heavy rain was expected Sunday, to Connecticut declared states of emergency. Delaware ordered mandatory evacuations for coastal communities by 8 p.m. Sunday.

Christie, who was widely criticized for not interrupting a family vacation in Florida while a snowstorm pummeled the state in 2010, broke off campaigning for Republican presidential nominee Mitt Romney in North Carolina on Friday to return home.

"I can be as cynical as anyone," the pugnacious chief executive said in a bit of understatement Saturday. "But when the storm comes, if it's as bad as they're predicting, you're going to wish you weren't as cynical as you otherwise might have been."

The storm forced the presidential campaign to juggle schedules. Romney scrapped plans to campaign Sunday in the swing state of Virginia and switched his schedule for the day to Ohio. First lady Michelle Obama canceled an appearance in New Hampshire for Tuesday, and Obama moved a planned Monday departure for Florida to Sunday night to beat the storm. He canceled appearances in Northern Virginia on Monday and Colorado on Tuesday.

In Ship Bottom, just north of Atlantic City, Alice and Giovanni Stockton-Rossini spent Saturday packing clothing in the backyard of their home, a few hundred yards from the ocean on Long Beach Island. Their neighborhood was under a voluntary evacuation order, but they didn't need to be forced.

"It's really frightening," Alice Stockton-Rossi said. "But you know how many times they tell you, 'This is it, it's really coming and it's really the big one' and then it turns out not to be? I'm afraid people will tune it out because of all the false alarms before ... (but) this one might be the one."

A few blocks away, Russ Linke was taking no chances. He and his wife secured the patio furniture, packed the bicycles into the pickup truck, and headed off the island.

What makes the storm so dangerous and unusual is that it is coming at the tail end of hurricane season and the beginning of winter storm season, "so it's kind of taking something from both," said Jeff Masters, director of the private service Weather Underground.