A recent story
claims that Bernie Sanders is planning to drop out of the Democratic race and run as an independent; he has denied it
. Donald Trump has said both that he would
and would not
consider running as an independent. If one runs and the other does not, that might well throw the election to the other side. The more interesting question is what happens if both run.
Sanders appeals to the left wing of the Democratic party, so the question is how many will vote their ideology at the risk of putting a Republican in the White House. Trump is a more complicated case, with positions on the right on some issues, the center, even the left on others. His appeal, so far as I can tell, is not ideological but personal—he is a more competent demagogue than the other candidates, a point persuasively argued
by Scott Adams of Dilbert fame. I would expect him to pull a significant number of votes from the Democrats although more from the Republicans.
If both run, how will the major parties respond? A Sanders campaign would pull Hilary left—arguably already has. A Trump campaign might give the Republican an incentive to try to match his demagoguery, as some are doing on the anchor babies issue. Or it might persuade the candidate that Trump's voters are a lost cause—and at least not voting Democratic. That could, to be unreasonably optimistic, improve the chances of Rand Paul or someone similar. And a Republican candidate Democrats only mildly dislike would reduce the incentive for Sanders supporters to vote for Hilary.
Commenters with better worked out ideas of the implications are invited to offer them.