With pundits predicting the closest United States presidential election since 1960, the role played by expatriate voters, such as the large American community in Switzerland, could be decisive.
Record numbers of US citizens living in Switzerland have registered to vote in this year's election contest between Texas' Republican governor, George W Bush, and Democrat Vice President Al Gore.
"The interest in this year's election has been incredible," says Kevin Crowley, chairman of Republicans Abroad for both Switzerland and Europe.
"It's going to be the closest election since the Kennedy-Nixon race in 1960. It will certainly all come down to the actual election night, which is rare," he told swissinfo.
His Democrat opposite number, David Dichter, agrees, saying American expatriates have been registering to vote in record numbers, aware that their ballot could be decisive.
"The number of people contacting me has been greater than ever before. Americans from all over Switzerland have been calling me every day for the past three months to ask how to register and get absentee ballots," Dichter says.
All of the votes have long since been cast, as postal ballots have to arrive by election day. But the two parties devoted a great deal of effort to voter registration in the summer and early autumn, in the knowledge that this election would be too close to call.
"There have been many races decided by... the overseas vote. The absentee ballots can amount to between two and three per cent in an election, which in a close year like this can tip the balance," Crowley says.
Votes from abroad are credited with maintaining the Republican majority in Congress in 1996. Some 15 seats were won with majorities no bigger than the size of the overseas ballots.
All seats in the House of Representatives are up for election again this year, as are a third of the Senate seats and a number of state governorships.
The parties are focusing on a number of key issues in a bid to win the support of their overseas constituencies.
The Republicans are emphasising the question of double taxation and the fact that American civilians living abroad were excluded from this year's census.
The Democrats hope to drive home the message that their party is more international in outlook. "Here in western Switzerland, a lot of Americans work for United Nations agencies or international organisations.
"They see the Democrats as being very supportive of international organisations, and as the party that will defend their interests.
"They get very concerned when they see people like (Republican Senator) Jesse Helms dictating foreign policy," Dichter says.
Both Dichter and his Republican counterpart, Crowley, are members of Geneva's sizeable US community. The city's American International Club stages the biggest 4th of July celebrations outside the United States, which attract around 50,000 people.
On Tuesday, the club will host an all-night election party. Democrats and Republicans will be able to let their hair down before the serious business of watching the continuous election coverage and finding out if it will be Gore or Bush in the Oval Office for the next four years.
What the gathering will demonstrate is that the election provides a crucial link with home.
"Many Americans become apathetic the longer they live abroad. But in an election year like this people become more tuned into the issues, after all they are being taxed without representation," Crowley says.
"We have some serious issues to deal with as Americans abroad. Those issues and the general domestic issues have got people very engaged in this election race."
David Dichter agrees: "This election has stirred them like no other before. Voting is one of the direct links they have with home and with the American political system. Those that are interested take being an American very seriously, and that means voting."
by Roy Probert