In the Democrat-dominated Yates bar in the Leicester Square nightclub district, voters clutching hot dogs and swigging bottled beer eagerly watched American news channels, awaiting early results from across the Atlantic.
The walls were plastered with campaign posters and US flags for the election party, the second largest in London after the US embassy bash across town. Organisers expect about 750 people to attend over the course of the night.
Mr David Grey, who runs a male salon in London, did not vote in the elections but supports Mr Barack Obama.
He hopes a Democrat victory would make it easier for Americans living and travelling abroad, by limiting the anti-American sentiment that has become widespread under President George W. Bush and since the invasion of Iraq.
'It would be nice to have a president who is celebrated when he goes abroad and his effigy is not burned,' he said.
As the bar filled up late on Tuesday, several Americans, who proudly noted they had voted via absentee ballot, were cautious about predicting the eventual winner between Republican John McCain and Democrat Obama.
If the customers at the bar had any say, though, Mr Obama would win by a landslide.
Staff noted that while several different patterns of the Democrat's clip-on shirt button had sold out, Mr McCain buttons had been outsold by those for libertarian candidate Bob Barr.
Party-goers also booed when staff announced that, along with CNN, Fox News channel - which is widely reviled by Democrats - would be shown on large LCD screens.
'There is no way in holy hell I would have voted for McCain,' said Ms Shelley Morin, an American student from Washington state who is studying at Goldsmith's College in London.
But like other Democrat supporters in the bar - who paid 35 pounds (S$81) each to attend the party - Ms Morin was wary of predicting a Mr Obama victory.
'I would love to hope for a victory, but I'm quietly cynical', she told AFP. 'I don't have much trust today'.
She added: 'I'm actually less concerned about Obama genuinely not winning enough electoral votes, than I am about (voting) machines, (misleading opinion) polls, lawsuits'.
Ms Joy Lee, a 32-year-old first generation US immigrant from Taiwan, held up her beer and jokingly noted: 'Well, if McCain does end up winning, I want to be drunk by then.' -- AFP