This is a very complex topic :) But firstly it is a theory of second-order elections. This SOE introduced the theory of Hermann Schmitt and Karlheinz Reif in book "Nine Second-Order National Eletions. A Conceptual Framework for the Analysis of European Election Results." A defined there about 6 characters less interested voters, smaller campaign, more profit smaller parties, etc. This theory created after the first direct elections in 1979. Then it was revised by many authors and is being tested in Europe and is still quite valid. The main idea is that anything less at stake in the theory of SOE. For voters are still in first place national elections, elections to the European Parliament are secondary.
The presidential election occurs on the first Tuesday after the first Monday in November every year that is divisible by four. The last presidential election was on November 4, 2008. The next will be on November 6, 2012, and after that one, the next will occur on November 8, 2016..
The most likely candidate to win would be Mitt Romney because he is the frontrunner in the 2012 Republican primary and because our current president Barrack obama has a low approval rating and has made no significant progress in our economy. Mitt Romney as of Monday October 15, 2012 he has a 9% lead in most polls.