Obama has edge over Romney

One of the closest presidential battles in recent American history

As President Barack Obama and Mitt Romney stormed into the last day of their long presidential contest, US psephologists claimed that the Democrat had an edge over the Republican.

The two campaigns' schedules left little doubt where the election would be won or lost: Obama was holding rallies in Wisconsin and Iowa. Romney was cutting a broader swath, with rallies in Florida, Virginia and New Hampshire. But the richest prize is Ohio, and on Monday 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 actually competing to win at least 270 electoral votes. The electoral votes 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 polls show the men locked in one of the closest presidential races in recent American history. But a majority of polls in the battleground states — especially in the Midwestern states of Iowa, Wisconsin and Ohio — show Obama with a slight advantage, giving him an easier path to the 270 electoral votes needed for victory.