A man with a small dog takes a photo of the storm waves from Hurricane Sandy in Ocean City, New Jersey, October 28, 2012. The hurricane forced both US presidential candidates to change their schedules. [Agencies]

Hurricane Sandy, bearing down on US shores, left its mark on the presidential race on Saturday, as President Barack Obama and Republican challenger Mitt Romney scrambled to get their campaigns out of the massive storm's path.

Romney canceled appearances in Virginia to head for Ohio ahead of the hurricane's arrival, while Obama moved up his departure to Florida — one of a handful of states where early voting got under way on Saturday.

The president was scheduled to travel to Florida late on Sunday for a rally that takes place on Monday.

Vice-President Joe Biden, meanwhile, canceled a visit to the battleground state of Virginia to allow law enforcement and emergency workers there to prepare for the advancing storm.

Sandy, which forecasters said could prove to be the most devastating storm in decades, currently is a category one hurricane, with the potential to bring its heavy rains and gusting winds when it makes landfall sometime next week anywhere from Virginia to New Jersey.

Forecasters predict the hurricane will collide with a seasonal "nor'easter", creating a supercharged, cold weather system that could burst through the Mid-Atlantic states as far inland as Ohio, in the all important final week before the Nov 6 election.

Romney and Obama are in a down-to-the-wire battle for the White House, in an election which most national polls have said is too close to call.

The outcome of the vote is expected to hinge on a handful of battleground states where the two contenders also, for the most part, are running within a few percentage points of each other in the polls.