Voters choose between Barack Obama and John McCain today

Voting underway in US elections

Voting underway in US elections

Polling stations are open across the United States as Americans elect their 44th president today.

Democrat candidate Barack Obama leads in the polls against Republican rival John McCain, who throughout much of the last six months has appeared the challenger, despite being from the same party as incumbent George Bush.

Both parties are now engaged in frantic operations to get their respective votes out. The race remains close in several key states, however, with Ohio, Indiana and Missouri well within the margin of error.

Polling has already closed in the small New Hampshire villages of Dixville Notch and Hart’s Location which have a tradition of voting shortly after midnight. Mr Obama won majorities in both.

Election day comes hours after Mr Obama’s grandmother, Madelyn Dunham, died aged 86 in Hawaii. He had taken a break from his campaign to visit her days before her death.

Although polls suggest a significant national lead for Mr Obama his opponent hopes battles in swing states will go in his favour.

“The Mac is back!” was his slogan yesterday as, in a marathon final day of campaigning, he visited Florida, Virginia, Pennsylvania, Tennessee, Indiana, New Mexico and Nevada.

Early exit polls expected shortly after midnight (British time) on Wednesday in battleground states Pennsylvania and Virginia will prove an indication as to which will be the eventual winner.

If Mr McCain succeeds in taking Pennsylvania, a state where Mr Obama holds a strong lead in the polls, attention will shift to western states like Nevada and Arizona.

In Nevada Mr Obama holds a four per cent lead, according to a Mason-Dixon poll, while in Arizona – Mr McCain’s home state – the American Research Group says the Republican holds the same tentative advantage.

Today’s vote will see the United States elect either its first black president – or its oldest ever.

At 72, Mr McCain insists he still has the youth and vigour to lead the country and has sought to emphasise Mr Obama’s lack of experience.

The Democrat has galvanised huge fundraising support, however, helping him afford a 30-minute infomercial broadcast across three national networks last week.

There are also fears the election may mirror previous votes and not go smoothly.

The 2000 election saw hanging chads and electronic voting difficulties in the decisive state of Florida delay the final result being called for several weeks.

And in 2004 Ohio, which proved the key to Mr Bush’s second victory, lengthy queues at polling stations as they closed caused controversy and delayed the eventual result.

Administrators say new voting machines have been drafted in to cope with the record numbers of voters expected today. And it is hoped postal ballot voting will ease pressures – a record 27 million have already voted.

Americans will also be electing Congressional representatives as well as participating in several gubernatorial races.

Democrats will be seeking to hit the ‘super-majority’ of 60 seats in the Senate, allowing them to prevent the Republicans’ favourite tactic of thwarting opposed legislation through filibusters.

And they will be hoping to make gains in the House of Representatives, where they currently hold 233 seats to the Republicans’ 202.

politics.co.uk will be covering events live from 22:00BST.