Last Updated 7:42 p.m. ET
After causing heavy damage and at least 58 deaths in the Caribbean, Hurricane Sandy is expected to make landfall on the East Coast by Tuesday. No one can be certain how powerful it will become, but the signs are ominous.
Sandy is expected to strike the Eastern Seaboard near the Delaware coast, then hit two winter weather systems as it moves inland, creating a hybrid monster storm.
Even if Sandy loses strength and makes landfall as something less than a hurricane, the combined storm was expected to bring misery to a huge section of the East. An 800-mile wide swath of the country could see 50 mph winds regardless of Sandy's strength.
Experts said the storm could be wider and stronger than Irene, which caused more than $15 billion in damage, and could rival the worst East Coast storm on record.
"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.
"This is not a coastal threat alone," said Craig Fugate, director of the Federal Emergency Management Agency. "This is a very large area."
Sandy weakened briefly to a tropical storm early Saturday but was soon back up to Category 1 strength, packing 75 mph winds about 335 miles southeast of Charleston, S.C., as of 5 p.m. Experts said the storm was most likely to hit the southern New Jersey coastline by late Monday or early Tuesday.
Tropical storm warnings are effect for parts of coastal North and South Carolina and Bermuda. Tropical storm watches were issued for coastal Georgia.
Meteorologist and CBS News hurricane analyst David Bernard of CBS Station WFOR says the storm weakened slightly overnight to a tropical storm, but was upgraded this morning to a hurricane packing 75 mph winds.
As of Saturday afternoon tropical storm-force winds are already near the coast of North Carolina.
Up and down the coast, people were cautioned to be prepared for days without electricity. Jersey Shore beach towns began issuing voluntary evacuations and protecting boardwalks. Atlantic City casinos made contingency plans to close, and officials advised residents of flood-prone areas to stay with family or be ready to leave. Several governors declared states of emergency. Airlines said to expect cancellations and waived change fees for passengers who want to reschedule.
The White House said President Barack Obama had a conference call Saturday to discuss Hurricane Sandy with the Homeland Security secretary, the head of the Federal Emergency Management Agency, the director of the National Hurricane Center and his homeland security adviser.
The White House says President Obama made clear to emergency management officials that the federal government should do all it can to provide resources to state and local officials along the East Coast as they brace for the approaching storm.
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. Saturday.
New Jersey's Chris 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 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 President Obama moved a planned Monday departure for Florida to Sunday night to beat the storm.
In Ship Bottom, just north of Atlantic City, Alice and Giovanni Stockton-Rossini spent Saturday packing clothing in the back yard 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, and the one time you need to take it seriously, you won't. 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.
"I've been here since 1997, and I never even put my barbecue grill away during a storm. But I am taking this one seriously," he said.
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.
Masters said the storm could be bigger than the worst East Coast storm on record -- the 1938 New England hurricane known as the Long Island Express, which killed nearly 800 people. "Part hurricane, part nor'easter -- all trouble," he said. Experts said to expect high winds over 800 miles and up to 2 feet of snow as well inland as West Virginia.
And the storm was so big, and the convergence of the three storms so rare, that "we just can't pinpoint who is going to get the worst of it," said Rick Knabb, director of the National Hurricane Center in Miami.