Battalions of lawyers are readying for legal challenges in battleground states after Tuesday's election, fearing a replay of the nightmare, razor-close 2000 contest in Florida between Democrat Al Gore and Republican George W Bush, who emerged victorious as President only after a Supreme Court decision.
With the 2012 election again too close to call, the Democratic and Republican parties have dispatched legal advisers to polling stations across the country with a particular focus on the politically polarised states of Ohio (where Democrats are understood to have deployed more than 2,000 legal experts), Florida, Wisconsin and Virginia, whose votes could decide the election outcome.
Experts say that their services will only matter if the number of outstanding absentee or provisional ballots is greater than the margin separating President Obama from his challenger, Mitt Romney. The tighter the result, the more likely legal challenges are.
Richard Hasen, law professor at the University of California, told the Associated Press that the problems "have to be widespread enough or the margin close enough that litigating would actually make a difference". A lawsuit has been filed over an 11th hour directive issued by Ohio's Republican Secretary of State, Jon Husted, which could invalidate an estimated 200,000 legal provisional ballots, cast when voters change their names or addresses.
Mr Husted's decision was challenged in court by voting rights advocates and he has until today to respond. The court has promised to resolve the dispute before the provisional ballots are formally counted on 17 November.
In Ohio in 2004, a recount was ordered in the contest between President Bush and his Democratic challenger John Kerry. A recount of the provisional ballots in a tight race between President Obama and Republican Mr Romney could delay the declaration of the election result for days.
Among other issues the lawyers may be called to adjudicate on are allegations of voter fraud and intimidation. Already in Florida, where early voting is underway, there have been long lines of voters outside polling stations and reports of people being turned away or discouraged from casting their vote after standing in line for hours. In a memo on Friday, the chief lawyer for the Democratic side, Bob Bauer, accused the Romney campaign of sending poll-watchers to challenge voter eligibility. But Romney campaign spokesman Ryan Williams said the charge was "ridiculous".
Other protests have concerned possibly malfunctioning electronic voting machines, after a woman in Marion, Ohio, complained that a touch-screen machine changed her vote for Mr Romney to one for Mr Obama.
On the Democratic side, lawyers have a computer system designed to track incidents at polling stations. The Republicans are using activists equipped with smartphones.
Potential voter fraud has been invoked by Republican state legislatures to push for new voter ID rules, but they were successfully challenged by Democrats in a number of states on the ground that they aimed to deprive minorities of votes.