It is decision day in America.

Voters will head to the polls to cast their ballots for the person they wish to have as President of the United States for the next four years.

President Barack Obama and Republican challenger Mitt Romney have closed out their hard-fought and deeply negative battle for the White House, yielding centre stage to voters who face a stark choice on Election Day between fundamentally different visions for the country's future.

After months of campaigning and billions of dollars spent in the battle for leadership of the world's most powerful country, Obama and Romney were in a virtual nationwide tie ahead of Tuesday's election, an overt symptom of the vast partisan divide separating Americans in the early years of the 21st century.

Obama appeared to have a slight edge, however, in some of the key swing states such as Ohio that do not vote reliably Democratic or Republican. That gives him an easier path to reach the 270 electoral votes needed to win the presidency.

Romney decided to make a late dash to Cleveland and Pittsburgh for rallies on Tuesday before returning to his Boston home to await the returns. Obama, who spent Monday night at his home on Chicago's South Side, opted to make a dozen radio and satellite TV interviews from Chicago to swing states to keep his closing arguments fresh in voters' minds.

Under the U.S. system, the winner of the presidential election is not determined by the nationwide popular vote but in state-by-state contests. The candidate who wins a state (with Maine and Nebraska being the exceptions) is awarded all of that state's electoral votes, which are apportioned based on representation in Congress.

Both sides cast the Election Day choice as one with far-reaching repercussions for a nation still recovering from the biggest economic downturn since the Great Depression and at odds over how big a role government should play in solving the country's problems.

``It's a choice between two different visions for America,'' Obama declared Monday in Madison, Wisconsin, asking voters to let him complete work on the economic turnaround that began in his first term. ``It's a choice between returning to the top-down policies that crashed our economy, or a future that's built on providing opportunity to everybody and growing a strong middle class.''

Romney argued that Obama had his chance and blew it. ``The president thinks more government is the answer,'' he said in Sanford, Florida. ``No, Mr. President, more jobs, that's the answer for America.''
   
Obama's final campaign rally, Monday night in Des Moines, Iowa, was filled with nostalgia as he returned to the state which launched him on the road to the White House in 2008 with a victory in its lead-off caucuses over Hillary Rodham Clinton, now his secretary of state. A single tear streamed down Obama's face during his remarks, though it was hard to tell whether it was from emotion or the bitter cold. The president had campaigned earlier in the day in Wisconsin and Iowa.

Fitting for a tight election, voters in tiny Dixville Notch, New Hampshire, split over the candidates, Obama and Romney receiving five votes each when balloting took place at midnight. In nearby Hart's Location, the hamlet that shares the traditional honour of casting the first presidential ballots on Election Day, Obama won with 23 votes, Romney received nine and Libertarian Gary Johnson received one.

More than 30 million absentee or early ballots have already been cast, including in excess of 3 million in Florida.

The forecast for Election Day promised dry weather for much of the country, with rain expected in two battlegrounds, Florida and Wisconsin. But the closing days of the campaign played out against ongoing recovery efforts after Superstorm Sandy. Election officials in New York and New Jersey were scrambling to marshal generators, move voting locations, shuttle storm victims to polling places and take other steps to ensure everyone who wanted to vote could do so.

(AP)