Barack Obama and Mitt Romney embarked on a final 10-day dash towards the election on Saturday, campaigning in battleground states as hurricane Sandy threatened to disrupt their schedule.

A new poll released as the candidates set out to woo swing voters in Florida and New Hampshire emphasised how important the final two weeks could be in the outcome of the 6 November national ballot. The Reuters/Ipsos survey of likely voter intention had Obama ahead by a whisker, leading Romney by 47% to 45%.

And research indicated that 88% of registered voters said they would definitely vote for one candidate or the other, leaving just 12% who are yet to decide who will get their nod for the White House.

The final days of campaigning will focus on that section of society in a handful of key states that are crucial to winning the presidential run-off.

On Saturday, Romney hopped on a plane in Ohio to head for a rally in Florida. Republicans are pinning their hopes to carrying both states if they are to oust Obama from the White House.

"Let's win this," Romney emailed to supporters in a rallying call Saturday, adding: "We're defying odds and holding strong."

His vice-presidential pick Paul Ryan was in Ohio Saturday morning to press home the Republican message.

At a factory in New Philadelphia, he told would-be voters: "You know what you have in front of you, you know your responsibility."

Meanwhile, the president opted to head to New Hampshire Saturday to start his 10-day countdown to election day. Before doing so, he used a new TV ad to urge Americans to consider Romney's plans to roll back Wall Street reforms, reduce education spending and turn Medicare into a voucher system.

At the same time, the Republican candidate planned to cut taxes for the super-rich, the attack ad added. The commercial will air in Florida, Iowa, Ohio and Virginia.

According to his official diary, Obama is due to head to Florida on Sunday before then going on the stump in Virginia, Colorado and Wisconsin early next week.

But campaign stops may be subject to change if hurricane Sandy wreaks havoc along the US's east coast, as some forecasters are predicting.

The so-called "super storm" has already killed scores of people in the Caribbean and is due to make landfall sometime Monday.

Even ahead of its official arrival, connected adverse weather conditions have taken a toll on the campaign plan of both sides.

Vice-president Joe Biden cancelled a rally at a coastal Virginia location planned for Saturday night to "ensure that all local law enforcement and emergency management resources can stay focused on ensuring the safety of people who might be impacted by the storm".

Likewise, Romney was forced to abandon plans for an event in Virginia Beach on Sunday.

Both presidential candidates have a delicate balance to maintain in terms of campaigning over the next few days.

With the race so tight it is crucial for them to appeal to the narrowing number of floating voters in key states. But neither can risk being seen putting political self-interest above of public safety.