I am sure it has been noted before, but as my Daily Kos Search Skills are limited, and I could not find a similar note, I am posting this information.
Most important fact that needs to be remembered about how the electoral college works and if no candidate receives a majority of electoral votes:
The candidate who receives an absolute majority of electoral votes (currently 270) for the office of president or of vice president is elected to that office. The Twelfth Amendment provides for what happens if the Electoral College fails to elect a president or vice president. If no candidate receives a majority for president, then the House of Representatives will select the president, with each state delegation (instead of each representative) having only one vote. If no candidate receives a majority for vice president, then the Senate will select the vice president, with each senator having one vote.
So if Mitt steps in as a third party candidate and Clinton/Sanders, Trump, and Romney split the electoral college with no majority, Mitt becomes President, and the republican candidate for Vice President takes office as well.
Now then I learned this on the web/wikipedia...so prove me wrong please.