Hurricane Sandy blew the US presidential race off course over the weekend even before it came ashore, forcing Republican Mitt Romney to shift his campaign inland and fuelling fears that the massive storm bearing down on the East Coast could disrupt early voting.
As much of the heavily populated region braced for what could be the largest storm to ever hit the US mainland, Romney re-routed his campaigning from Virginia to Ohio, another of the handful of battleground states that will decide the outcome of the 6 November election.
Juggling both his re-election attempt and efforts to stay on top of the hurricane's impact, President Barack Obama was due to visit the government's storm-response center in Washington before travelling to Florida for a campaign event. The storm has forced Obama to reschedule events on Monday and Tuesday.
Officials in the path of the storm scrambled to ensure that extended power outages would not disrupt the early voting that appears to be more important than ever for both sides this year.
"Obviously we want unfettered access to the polls because we believe that the more people that come out, the better we'll do," top Obama advisor David Axelrod said on CNN. "I hope that it all clears out and by the next weekend, we'll be free of it."
Virginia Governor Bob McDonnell, a Republican and prominent Romney supporter, said the swing state plans to extend early voting hours and restore power quickly to voting facilities in the event of outages.
"It's now a priority, moved up to the same level as hospitals and police stations, to have power restored" at voting facilities, he said.
The looming storm threw another note of uncertainty into a race that remains a statistical dead heat. Political scientists believe natural disasters can hurt an incumbent's re-election chances as voters often blame whoever is in office for adversity.
Larry Bartels of Vanderbilt University and Christopher Achen of Princeton University examined rainfall data back to 1896 and found that extreme droughts or floods cost the incumbent party office holders an average of 1.5 percentage points of the vote total.
Severe drought and excessive rainfall probably cost then Vice President Al Gore victories in seven states in the 2000 election, enough to hand the contest to Republican George W. Bush, they found.
Bush's approval ratings plummeted after Hurricane Katrina devastated New Orleans in 2005, and voters could similarly blame Obama if the government fumbles its response to this storm.
But there are also dangers for Romney who will have to be careful to avoid being seen as politicising the disaster. His campaign's hasty response to the attacks on U.S. diplomatic missions in the Middle East in September was widely criticised.
Most voters have made up their mind
The vast majority of voters have made up their minds at this point, and nearly one in five have already cast their ballots. But the storm could throw a wrench in the campaigns' efforts to drive voters to the polls in the final days before the election.
Opinion polls show the race to be essentially tied at the national level, but Obama retains a slim advantage in many of the battleground states that will decide the election.
A Washington Post poll released on Sunday found Obama leading Romney by 51% to 47% in Virginia, just outside the poll's margin of error.
In Ohio, a poll by a group of newspapers found the two tied at 49% each. Other polls have shown Obama ahead there.
Republicans argue that Romney has the advantage at this point because he has narrowed the gap since the beginning of October.
"When you have the momentum and you're a challenger in a tie race, the challenger wins," Republican National Committee Chairman Reince Preibus said on CNN.
Democrats point to the high level of early voting among supporters as evidence that Obama is in good shape.
"That's a sign that there is momentum behind the president's re-election, there is energy on the ground. We're a little over a week out, and we're confident," Obama campaign adviser Stephanie Cutter said on ABC television's "This Week."
Romney received the endorsement of Iowa's largest newspaper, the Des Moines Register, which has not backed a Republican since 1972. He also won the endorsement of newspapers in Richmond and Cincinnati.
Obama won the endorsement of newspapers in Miami, Detroit and Toledo, Ohio, as well as The New York Times.
President Barack Obama and his Republican challenger Mitt Romney are beginning their last week drive to US election day on 6 November, following their third and final televised debate.
The campaign comes down to one number: 270. That's the number of electoral college votes both sides need to win and to claim the White House. The electoral college was created in the earliest days of the US as a voting system that allows the disparate states to come together and elect a single president to represent them all.
Each state, plus Washington, DC, is awarded a certain number of electoral votes based roughly on size. California, America's largest state, gets 55 votes while sparsely-populated Wyoming gets only three. All but two states use a winner-takes-all system. There are 538 electoral college votes in total.
- 6 November: Americans go to the polls