US expatriates in London on Wednesday bedded in for all-night parties fueled by homely refreshments as they nervously awaited the results of the presidential election.

Guests at the US embassy in the British capital donned red, white and blue party hats and pin badges of candidates Barack Obama and Mitt Romney while they watched huge screens transmitting the latest poll results.

Bartenders kept the party lubricated with craft beers from Chicago and New York while waiters topped up energy levels with the most famous of US delicacies -- McDonald's Big Macs and chicken nuggets.

The embassy in London's exclusive Mayfair district also put on entertainment in the "Regal Eagle" room with musician James McCartney, son of Beatles star Paul, helping supporters dance away the tension.

Ambassador Louis Susman told AFP that the event gave Americans and interested Britons "an opportunity to enjoy and watch democracy in action".

"There will be umpteen millions of people voting, and we are here to celebrate that event," he added.

"It's exciting, it's close. That makes people excited, and everybody is rooting for their man and enjoying themselves."

Meanwhile, a mile away in the Sports Bar and Grill, around 500 confident Democrat supporters cheered as early results and exit polls suggested that President Obama was edging the contest.

Party-goers armed with large cardboard cutouts of the president and US flags gave a particularly lusty roar at 1:00 am (0100 GMT) when exit polls showed Obama leading in the crucial swing-state of Florida.

But there was plenty of beer still to be drunk and chicken wings to be devoured before the champagne could officially be cracked open.

Kate Hedges, originally from New York but a London resident for 20 years, told AFP she had faith in a positive outcome for her candidate.

"I'm not only hopeful, I'm confident," she said. "There's a great atmosphere here, and it's only going to get better.

"Intellectually, Obama's my guy. This election in many ways has been a debate on the size of government, and I think Romney's government is too small."

However, Republican supporters at the embassy party were not ready to throw in the towel despite the discouraging data.

Republicans Abroad member and Pennsylvania native Greg Bentley, 57, warned that anything but a Romney victory could be disastrous for the US.

"I'm optimistic, but I'm nervous," he said of the result.

"There are some people in the US who like President Obama, but there's none of us who can afford him," he told AFP.

"In four more years, the country could be bankrupt and we are certainly on the road to Greece."

[Image via Agence France-Presse]