Barack Obama has edged ahead of his rival Mitt Romney in the final days of the presidential campaign, as experts predicted a photo-finish to one of the closest elections in American history.
A new poll for the Pew Research Center holds a 48% to 45% lead for Obama over Romney among likely voters.
As the candidates raced across the US in the final frenetic days of campaigning the polls are thought to indicate Obama was helped by his handling of the aftermath of Superstorm Sandy.
The poll of 2,709 likely voters, which has a margin of error of 2.2 percentage points, indicates a modest lead for Obama - the final estimate based on the figures being Obama at 50% and Romney at 47%.
Last week another Pew poll had the candidates neck-and-neck at 47% among likely voters.
That poll was, however, held before the superstorm battered the East Coast of the US.
The numbers suggest that Obama's handling of the storm may have improved his showing with 69% of likely voters saying they approved of the way Obama dealt with the impact of the storm.
Even among Romney supporters Obama polled 46% in support of his handling of the crisis. The biggest number was, however, 63% among the crucial swing voters.
The findings of the poll are broadly similar to those of the Wall Street Journal/NBC poll that was published this weekend - the two surveys are the first to indicate the possible impact of the storm, which has claimed the lives of 110 people so far, and left thousands without electricity, on the outcome of the election.
The poll news came as Obama and his challenger Mitt Romney fired into the last day of their long presidential contest, mounting a final thrust before Election Day and engaging in the toughest battleground state - Ohio.
The two campaigns' schedules left little doubt where the election would be won or lost: Obama was holding rallies in Wisconsin and Iowa. Romney is in Florida, Virginia and New Hampshire.
The richest prize is Ohio, and today both Obama and Romney were rallying their supporters in its capital, Columbus.
Under the US system, the winner is not determined by the nationwide popular vote but in state-by-state contests, making these nine “battleground” states that are neither consistently Republican nor Democratic extremely important in such a tight race.
Romney and Obama are competing to win at least 270 electoral votes. They are apportioned to states based on a mix of population and representation in Congress.
That raises the possibility of a replay of the 2000 election when Republican George W Bush won the presidency with an electoral vote majority, while Democrat Al Gore had a narrow lead in the nationwide popular vote.
Nationwide it still looked today as though the race could be one of the tightest in US history.
According to Associated Press, if the election was held today Obama would be all but assured of 249 electoral votes, by carrying 20 states that are solidly Democratic or leaning his way — Iowa, Nevada and Pennsylvania among them — and the District of Columbia.
Romney would lay claim to 206, from probable victories in 24 states that are strong Republican turf or tilt toward the Republicans, including North Carolina.
Up for grabs are 83 electoral votes spread across Colorado, Florida, Ohio, New Hampshire, Virginia and Wisconsin.
Of those, Republicans and Democrats alike say Obama seems in slightly better shape than Romney in Ohio and Wisconsin, while Romney appears to be performing slightly better than Obama or has pulled even in Florida and Virginia.