Obama or Romney? Five scenarios that could affect the outcome of the election

The memory of 2000 hangs over next Tuesday's election. Could we wake up on Wednesday with the result undecided?
Obama buttons in New York City
Buttons of President Barack Obama are displayed at a table set up by the Three Peaks Independent Democrats in the Upper West Side of Manhattan. Photograph: Spencer Platt/Getty Images

The memory of Bush versus Gore will be hanging over next Tuesday's election like a black cloud. Could it be possible that, as in 2000, we wake up on Wednesday morning with the next occupant of the White House still undecided?

Quite possible, says Professor Edward Foley, an expert in election law at Ohio State University. He estimates, based on his knowledge of the legal landscape and his reading of the polls, that there could be up to a 1% chance of the outcome of the election still being in the balance beyond next Tuesday.

He goes further. He says that the US should embrace the possibility of a delayed result as a necessary and healthy part of the electoral process in the advent of a very close race. "Just because we are forced into overtime on 7 November doesn't automatically mean we are in crisis," he says. "Such uncertainty is not a reason for panic."

Here are some possible doomsday scenarios that could leave us still guessing next Wednesday morning:

Storm Sandy

As the fallout of the storm continues to play out across several north-eastern states, the question arises could major disruption to voting centres cause a delay. It's possible, though highly unlikely, that Congress could pass legislation postponing the election. Federal officials have indicated that individual states should decide. Those most affected by the storm, notably New Jersey and New York, are so firmly Democratic that there is no doubt about their outcome. Virginia is the only battleground that has been heavily affected, yet latest estimates suggest power should be restored in most areas of the state by Friday.

Too close to call

It's possible that a state whose crop of electoral votes could determine the identity of the next president – Florida with 29 votes, perhaps, or Ohio with 18 – could be so close that either candidate refuses to concede and demands a recount. Florida's recount debacle in 2000 famously went all the way to the US supreme court and was finally awarded to George Bush by just 537 votes. It's also possible that several states are too close to call, leading to a multiple agony of indecision. That happened in 1916, with America's position in the first world war hanging on the election, when so many states were exceptionally close that Woodrow Wilson's victory over Charles Hughes was delayed for many days. In 1876, four states were in dispute, pushing back the victory of Rutherford Hayes for months to the eve of his March inauguration.

If a recount happened in Ohio next week it could delay the final result of the presidential race until 11 December.

Provisional ballots

In an attempt to avoid the 2000 snarl-up repeating itself, Congress passed the 2002 Help America Vote Act to try and modernise the system. That has increased the role of provisional ballots, which are cast by voters where there is a question mark over their eligibility and are counted after election day. Several swing states – for instance Colorado, Florida, Nevada and Virginia – have had substantial numbers of provisional ballots in recent elections. The phenomenon is particularly acute in the key battleground state of Ohio where more than 200,000 provisional ballots were cast in 2008. Were sufficient provisional ballots cast this year in Ohio to put a close result in jeopardy, then the outcome in Ohio and thus potentially in the entire presidential race could be delayed until 17 November.

Absentee and military ballots

It is conceivable that a dispute could erupt over absentee or military ballots in a very close race. Consider what happened in Minnesota in 2008, where Al Franken's eventually successful challenge to the incumbent senator Norm Coleman was delayed by more than seven months by wrangling over absentee ballots.

Colorado, Florida and Virginia all have large military bases and are therefore likely to have a substantial number of military ballots which could be important in a razor-close vote.

A 269-269 tie

It takes 270 electoral votes to earn the keys to the White House. It is theoretically possible that there could be a tie between Obama and Romney of 269 votes to 269. In that event, the House of Representatives would choose the president in a ballot to be held in January in which each state delegation in the House would have one vote. The vice-president would be chosen by the Senate. Pundits have had a lot of fun envisaging the remote prospect that Mitt Romney is elected Republican president with Joe Biden as his Democratic vice-president.