President Barack Obama is to resume an election campaign suspended in the aftermath of storm Sandy, which wreaked havoc in the north-eastern US. Mr Obama visited storm-hit New Jersey on Wednesday, while Republican rival Mitt Romney has been holding rallies after restarting his own campaign. Meanwhile New York's first subway train set off since Monday, when the network closed for the storm. Sandy left at least 64 dead in the US, laying waste to much of the east coast. It cut power from millions of homes and paralysed transport. The storm made landfall on Monday night in New Jersey, where some 20,000 people remain trapped in their homes by sewage-contaminated floodwater. In New York City, the storm brought a record tidal surge that swamped the subway system and caused widespread blackouts. Earlier, it killed nearly 70 people in the Caribbean and caused extensive crop destruction in impoverished Haiti. 'Long haul' Mr Obama has planned campaign stops on Thursday in Nevada, Colorado and Wisconsin. On Wednesday, he toured parts of New Jersey struck by the storm with Republican Governor Chris Christie. "You guys are in my thoughts and prayers," the president said during a visit to an emergency shelter in Atlantic City. "We are going to be here for the long haul." Of more than six million homes and businesses across the north-east that still have no electricity, a third of them are in New Jersey. In the New Jersey city of Hoboken, across the Hudson River from New York City, the National Guard has arrived to evacuate about 20,000 people and distribute meals. New Jersey Governor Chris Christie, usually one of Mr Obama's fiercest critics, spoke of his "great working relationship" with the Democratic president. "I cannot thank the president enough for his personal concern and compassion for the people of our state," said Mr Christie. Mr Romney held two rallies in Florida on Wednesday, where his campaign said he tried to strike a "positive tone". Election day is on 6 November, and polls suggest the candidates are running neck and neck. Eight out of ten voters in a Washington Post/ABC poll gave Mr Obama an "excellent" or "good" rating for his handling of the emergency. New York began a slow recovery from the storm on Wednesday. The New York Stock Exchange reopened on generator power after two days of closure, along with the Nasdaq. But New York City's Bellevue Hospital had to order the evacuation of some 500 patients after back-up electricity failed. Many bus services are already back on the roads, and most of the city's bridges have reopened. The Holland Tunnel, connecting New Jersey and New York City, remains flooded. Flights have now resumed at JFK and Newark Liberty airports, though the city's LaGuardia airport remains closed. Nearly 20,000 flights were grounded by Sandy.