There is a nascent but rapidly growing effort from supporters of Hillary Clinton to persuade presidential electors who would otherwise support Donald Trump to cast votes for Mrs. Clinton instead when the Electoral College meets December 19. Absent an extraordinary change of circumstances, it simply won't happen. Mr. Trump will win a majority of electoral votes on December 19 and become the 45th president of the United States.

It's worth noting that a lot of options to affect the presidential outcome have long since past--usually, waiting until after the election is not a good idea to affect an election.

I wrote back in March that state legislatures could choose their own electors instead of leaving the matter to a popular vote; but after a popular vote was held November 8, that strategy is not an option.

I also wrote in August that parties could select electors inclined to support their preferred candidate. The electors, however, have already been selected.

Instead, the only strategy for Mrs. Clinton's supporters is to turn to the Electoral College itself and persuade electors to be "faithless"--that is, persuade them to vote not for Mr. Trump, to whom they pledged (formally or informally) their support, but Mrs. Clinton.

First, it's worth noting that these are loyal Republicans who were selected as Trump electors. Many of them are loyal Trump supporters. The list of viable options, then, is limited to those who oppose Mr. Trump--and not just oppose him, but affirmatively prefer Mrs. Clinton (more on that point below). And this after Mr. Trump has won the election (at least, by all popular reports). It might be that Mr. Trump is not overly popular with many in the Republican establishment. But convincing them now to vote for someone else seems impossible.

Furthermore, these are electors in states that cast a plurality of their votes for Mr. Trump. Going to them and telling them to ignore the wishes of the voters in their own state for the wishes of the country as a whole--which, really, is overwhelmingly the wishes of California and New York--is even more unlikely.

Second, the electors would need to flip to Mrs. Clinton, and not simply refuse to vote for Mr. Trump. In order for a candidate to win, he must secure 270 electoral votes. If he fails to do so, the race is thrown to the House of Representatives, where each state receives one vote, and a majority of the states (26) is required to secure the presidency. Even if enough Trump electors threw all their votes to, say, Mitt Romney, no one would have a majority, the election would go to the House, and the Republican-controlled House where Republicans control a majority of state delegations would, in all likelihood, simply vote for Mr. Trump--absent yet another colossal effort to convince them to change their minds and somehow vote for Mrs. Clinton.

Third, the margin of victory is onerous for Mrs. Clinton's supporters. It appears Mr. Trump has won at least 290 electoral votes, meaning 21 electors would need to switch to Mrs. Clinton to deny him a majority, 22 electors to give her a majority, and 23 or 24 electors to account for Mrs. Clinton's own possible "faithless" electors. If he holds onto Michigan, she'll have secured 306 electoral votes, meaning the numbers increase to 37, 38, and 39 or 40.

These are Herculean numbers under almost any scenario. Consider that in the last 100 years, just nine (depending on your math) electors have been "faithless" and voted for someone other than the person pledged to support. Granted, no such concerted effort has been made to change electors' minds. Robert M. Alexander has surveyed presidential electors and discovered that serious lobbying efforts have occurred before, and that about 10% of electors in previous elections have considered voting for someone else--but did not do so.

Fourth, a few states purport to bind their electors to the individuals they are pledged to support. I've argued such laws may well be unconstitutional and should be repealed. But as they are on the books, it would either limit the pool of possible electors who could change their minds or stir litigation, possibly in multiple states, that would inspire even greater complexity, particularly if Congress is faced with multiple slates of electors.

In short, there is no realistic chance that the Electoral College will change the result of this election. This is different than saying it is not legally possible; as I've noted and defended repeatedly, electors are permitted to vote for whomever they desire--it is that there is essentially no likelihood enough of the would do so in such a way to change the outcome of the election. Circumstances change, of course, and something might still inspire a significant number of electors to change their minds and vote for someone else. But the odds are low. And we have fairly settled expectations that our electors will not be "faithless," something unlikely to change in the weeks ahead.