One more thing to add to the list of potential nightmare scenarios if the presidential election is extremely close: Provisional ballots that aren't counted for days or weeks.
Voters cast provisional ballots for a variety of reasons, including failing to bring ID to the polls, not updating voter registration after moving or trying to vote at the wrong precinct.
A federal election law passed after the 2000 presidential election gives voters the option to cast a provisional ballot, if poll workers deny them a regular one. In Ohio and Pennsylvania, voters who don't bring an ID to the polls can still have their votes counted if they produce an ID after Election Day. In Ohio, provisional voters have up to 10 days post-election to produce an ID.
If voters in Florida don't bring an ID to the polls, they must sign a provisional ballot envelope. Canvassing boards then will try to match the signatures with those in voter registration records, a process that conjures up images of the 2000 presidential election in Florida.
"It's a possibility of a complete meltdown for the election," said Daniel Smith, a political scientist at the University of Florida.
— Stephen Ohlemacher — Twitter http://twitter.com/stephenatap
EDITOR'S NOTE — Election Watch shows you Election Day 2012 through the eyes of Associated Press journalists. Follow them on Twitter where available with the handles listed after each item.