At the risk of engaging in a hit-and-run argument, I wanted to go on record to say that I think this is a bad idea. My reasons are best encapsulated in this tweetstorm by the political scientist Matt Glassman, who notes that there is a strong precedent toward electors abiding by the vote in their states. Other than a few one-off cases like Leach, the historical norm has been that electors stick with the voters’ choice unless the candidate died, as in the case of Greeley or the losing vice presidential candidate James S. Sherman in 1912. Furthermore, as Glassman notes, it’s not at all clear what the upside for Democrats would be. This year, narrowly denying Trump a majority in the Electoral College would still probably result in Trump’s election via the Republican-controlled House of Representatives, producing the same president but with a Constitutional crisis along the way. And in the long run, encouraging electors to deviate from the outcomes in their states would result in the House more often deciding presidential elections, which is probably not in Democrats’ interests given how their voters are clustered — and gerrymandered — into urban congressional districts.
Besides, the Constitution provides for other remedies to deal with a president whom voters perceive to be illegitimate or unfit. He can be impeached. Lesser known: In the event of a physical or mental disability, he can be temporarily relieved of duty under the 25th Amendment. He can, of course, be voted out of office after four years.
And in the meantime, voters can check the president’s power by electing members of Congress to oppose him, or by pressuring the current Congress to do so.