First things first: Article 2, Section 1 of the US Constitution determines the make-up of the Electoral College:
Each State shall appoint, in such Manner as the Legislature thereof may direct, a Number of Electors, equal to the whole Number of Senators and Representatives to which the State may be entitled in the Congress: but no Senator or Representative, or Person holding an Office of Trust or Profit under the United States, shall be appointed an Elector.There is no specific requirement for how states select their electors. The same section, as amended in the 12th Amendment, talks about what the Electors do:
The Electors shall meet in their respective states and vote by ballot for President and Vice-President, one of whom, at least, shall not be an inhabitant of the same state with themselves; they shall name in their ballots the person voted for as President, and in distinct ballots the person voted for as Vice-President, and they shall make distinct lists of all persons voted for as President, and of all persons voted for as Vice-President, and of the number of votes for each, which lists they shall sign and certify, and transmit sealed to the seat of the government of the United States, directed to the President of the Senate; -- the President of the Senate shall, in the presence of the Senate and House of Representatives, open all the certificates and the votes shall then be counted; -- The person having the greatest number of votes for President, shall be the President, if such number be a majority of the whole number of Electors appointed…So, there is no Constitutional requirement that Electors vote for whoever won their state’s popular vote. If they don’t, they’re what’s called a “Faithless Elector”, although the term applies to an Elector who doesn’t vote for the winner in the state for any reason.
This means that—under the Constitution—Electors can vote for whoever they want to. However, some states require electors to pledge to vote for whoever won their state’s popular vote, and the Supreme Court has upheld the requirement of such a pledge.
Some states go further and require Electors to vote for the candidate who won the state’s popular vote, and some have laws to impose penalties on any who don’t. However, the Supreme Court has never ruled on the constitutionality of such laws, and it’s probable that they’re unconstitutional because Electors were intended to be free to vote for whoever they wanted to as a check against citizens electing someone unqualified to be president (ahem…).
In considering all this, It’s important to know that Electors are chosen, one way or another, by the parties in each state so that they’re believed to be certain to vote for their party’s candidate. It hasn’t always worked out that way, of course, but it’s very rare for any Electors to go against their party.
Naturally, this affects the two competing proposals and the likelihood (or not) of their success.
One proposal has a Change.org petition to ask Electors to vote for Hillary Clinton, mainly because she won the popular vote. This is unlikely to happen because the Electors are chosen by state parties, so it means asking Republican Electors to vote for Hillary Clinton instead of their party’s nominee. That seems, to say the least, highly unlikely.
The other proposal is to write to the 160 Republican Electors in states that don’t legally bind their Electors and ask them to vote for any Republican other than Don. This could happen and is perfectly legal and constitutional, and doesn’t make the Electors to take a risk in defying a state’s laws—but what happens then?
Back to Article II Section 1 (as amended):
“…The person having the greatest number of votes for President, shall be the President, if such number be a majority of the whole number of Electors appointed; and if no person have such majority, 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; a quorum for this purpose shall consist of a member or members from two-thirds of the states, and a majority of all the states shall be necessary to a choice.So: If no candidate for president has 270 Electoral Votes, the House of Representatives chooses the president, which each state getting one vote. What would happen then? No one knows. How state delegations would vote would depend, in part, on which party has more seats in each state’s delegation in the US House, how many state delegations the teabagger faction of the Republican Party dominated, and, most importantly, who the other Republican candidate was (Paul Ryan wouldn’t get any teabagger votes, for example).
What this means is that the second (and more probable) proposal could work, but the country could still end up saddled with Don as president. Pence would be vice president regardless because no one is suggesting that Electors choose an alternative (and that means it’s theoretically possible that Hillary Clinton could be president and Pence could be vice president).
The bottom line, then, is that either proposal could happen, though the second would be far more likely to succeed, but even if the second one did happen, the country could still end up with Don. That means it’s unlikely to happen at all.
Should they do it? That’s a matter of individual conscience, but the reasons for it are that, first, it might rid the country of the nightmare that Don as president will be, and it would do so in a peaceful, legal, constitutional way. It could also see the constitutionality of the whole “Faithless Elector” thing determined by the Supreme Court.
However, if either Faithless Elector scenario were to succeed, there would probably be at least routine violence from Don’s most ardent fans, and they’d probably even launch outright armed insurrection. Although we can’t know for certain that would happen, it does seem likely—is that risk really worth it when it’s unlikely to succeed? Worse, if things get all the way to the House of Representatives and Don still becomes president, then he would be massively empowered to become even more radical than he otherwise might have been. These are the risk that Electors would have to weigh in deciding what to do.
Could denying Don the Electoral College majority happen? Yes. Will it? Almost certainly not. Should it? I’ll say this: I’m glad I’m not a Republican Elector!
However, maybe all of this will finally stir Americans to do what should have been done decades ago: Abolish the Electoral College. Republicans have now twice in this young century won the presidency even though they lost the popular vote: The Democratic candidate won the majority of the popular vote in four of the five presidential elections from 2000 onwards, but only won the presidency two of those times. This is precisely why Republicans won’t back the Constitutional Amendment needed to make the president elected by popular vote: They're unlikely to win the White House without the Electoral College.
But they can’t hold out forever, and maybe this will help push the cause along.
Update – November 15: The National Constitution Center has published an excellent explanation of why nothing much unusual will happen on December 19 and Don will become the next president. However, since the article was published, Hillary Clinton officially won the four Electoral Votes from New Hampshire, not that it matters.