In an extremely close presidential election it is possible that no candidate could get the needed majority of 270 Electoral votes. The Constitution of the United States makes provision for this scenario.
The Twelfth Amendment (ratified June 15, 1804):
This states in layman’s language that if no one presidential candidate gets the required majority, than the House of Representatives would choose immediately, by ballot, the President. However, it is important to note the vote would be by states, the representation from each state would have one vote. So each Representative does not get one vote, rather each state represented in the House gets one vote.
Again if no one vice-presidential candidate gets a majority of Electoral votes, then the Senate would choose the Vice-President from the two candidates with the most Electoral votes.
This system raises an interesting scenario. If both the presidential and the vice-presidential candidate did not receive a majority of Electoral votes, both would be elected by Congress, the House of Representatives the President, and the Senate, the Vice-President. This election if the Senate stays Democratic and the House stays Republican as expected then the likely scenario in this rare case would be President Romney and Vice-President Biden for the next four years.
What an interesting administration those would be. History consists of what-if scenarios. Some come true and others don’t. Watch closely to see what happens here.