Polling day dawns for Obama and McCain

Americans go to the polls to 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.

The race remains close in several key states, however, with Ohio, Indiana and Missouri well within the margin of error.

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

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.

Now the campaigning is over and both parties will be focusing on getting their voters out to the polls.

As usual attention will be focused on the weather, which often plays a major role in turnout.

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 – around 20 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.