We have added the ability to calculate tie scenarios to The Road to 270 on the 2012 election map. This is part of “The Road to 270” feature, which is displayed below the election map when neither candidate has 270 electoral votes and there are 12 or fewer states undecided on the map you have created.
An electoral college tie can occur since there are an even number of electoral votes (538) available. It would occur if each candidate in the 2012 presidential election ended up with exactly 269 electoral votes, one fewer than the required 270.
If neither candidate gets a majority of the Electoral Votes, the election for President is decided in the House of Representatives, with each state delegation having one vote. Senators would elect the Vice-President.
It is important to note that an apparent tie on election night does not mean that there is actually a tie. The actual Electors meet on the first Monday after the second Wednesday in December (December 17, 2012) to cast their votes. Only about half the states have laws requiring their Electors to vote for the popular vote winner. It is possible that an Elector could cast his or her vote for another person. As long as that vote wasn’t for the other major candidate in the race, this wouldn’t be an issue — neither candidate would have 270. However, imagine a scenario where a single Elector in a single state switched their vote to the other party — the vote would be 270 -268. While very unlikely, it has happened before (most recently in 1968, although the election that year wasn’t close).
More than likely, the election would remain undecided after the Electors voted. The decision would then fall to the new Congress (the one to be elected in November, 2012). After they are seated (likely the first week of January, 2013), the new Congress will count the electoral votes (this count happens whether the election is close or not). If neither candidate has reached 270 Electoral Votes, then the House and Senate take over and elect the President and Vice-President, respectively.