Let’s set aside the controversy about whether to have an Electoral College; instead, let’s ask: What happens if no candidate gets a majority vote?
Well, under the original Constitution, the plan was very badly busted: Under art. II, § 1, cl. 3, each elector was supposed to cast two votes, without indicating which was for President and which was for Vice-President; the candidate who got the most votes would be President (assuming he got at least enough votes to account for a majority of electors), and the first runner-up would be Vice-President. But say that, today, each Republican elector casts a vote for Romney and a vote for Ryan, and each Democratic elector casts a vote for Obama and a vote for Biden. Whichever party wins, there would be a tie, either a Romney-Ryan tie or an Obama-Biden tie. No-one would get the most votes, so you’d need to do a weird tiebreaker (more on that below) through the House of Representatives.
Indeed, in 1800 this is what happened, with Jefferson (the Presidential candidate of the Democratic-Republicans) and Burr (the Vice-Presidential candidate) ending up tied, and zaniness ensuing. What’s more, the 1796 election had by then already produced a Federalist President (Adams) and a Democratic-Republican Vice-President (Jefferson), which itself wasn’t very good. The result was the Twelfth Amendment, enacted in 1804, just 15 years after the original Constitution, that was meant to fix these problems.
And it did go a long way to fixing the problems, by having each elector vote separately for the President and the Vice-President. But what happens if no-one gets a majority of the electoral vote, either because three candidates split the electoral vote, because enough electors refuse to vote for the candidate that they were expected to vote for, or because the electoral college splits evenly (today, 269-269)? Well, here’s what happens:
[I]f no person have [a] majority [of electoral votes for President], then from the persons having the highest numbers not exceeding three on the list of those voted for as President, the House of Representatives shall choose immediately, by ballot, the President. But in choosing the President, the votes shall be taken by states, the representation from each state having one vote ....
[I]f no person have a majority [of electoral votes for Vice-President], then from the two highest numbers on the list, the Senate shall choose the Vice-President ....
So the House, voting by states, elects the President, but the Senate, voting by Senators, elects the Vice-President. And, as ABC News notes, the majority of House delegations is Republican, and would thus presumably vote for Romney; this will likely stay this way following the election. But if the Senate majority remains Democratic, then the Senators will presumably vote for Biden. (I think it will be the newly enacted House and the Senate with the newly elected Senators who will vote, because 3 U.S.C. § 15 provides that Congress’s involvement in the election of the President — even just the process of counting electoral votes when there is a clear majority — begins January 6, and the Twentieth Amendment provides that the terms of newly elected Representatives and Senators begin January 3.)
What’s more, this is eminently predictable — by the time the Twelfth Amendment was enacted in 1804, American leaders were well aware that parties would be important, and that Presidential and Vice-Presidential candidates would run on tickets together. Yet the Twelfth Amendment provided for selection of the President and Vice-President by two different processes, which might well yield different results. Indeed, the Amendment contemplates that sometimes the #3 Presidential candidate would win (presumably as a compromise). But in that situation, assuming all the electors voted in the first place for the preplanned Presidential/Vice-Presidential tickets, the Vice-President who is elected will be guaranteed to not be the President’s choice, since the President is chosen from the top three vote-getters but the Vice-President only from the top two.
Of course, in all these scenarios we’re not talking about frustrating the will of the majority (at least if we accept the electoral college as a filter for public sentiments) — by definition, there won’t be a majority. And the President and Vice-President need not work closely together; indeed, as I understand it, throughout American history they often haven’t.
But it’s still important, I think, that in the event the President dies or becomes disabled, the agenda of the Administration continue without massive interruption — and a sudden, unplanned switch in the middle of a presidential Term from one party to another is likely to be such an interruption. (I’m no historian of the Civil War era, but as I understand it much of the problems that Andrew Johnson faced stemmed from his being of a different party from Abraham Lincoln; the two were elected on a wartime unity ticket.) So the Framers of the Constitution, and then the authors of the Twelfth Amendment, seem to have erred in this respect, though as to circumstances that, admittedly, are quite rare in American history.