In your original letter, you stated:
I keep hearing that Bernie can still win, and that he's the only one who can beat Trump in a general election. What's your take on that?
Bernie's "lead" in the general comes only from the
#BernieorBust movement, which based on demographics aren't incredibly likely to vote in the general anyway.
Your argument for why your candidate is more likely to win is because your candidate has supporters who would throw the election to Trump if he doesn't get the nomination.
That's like me saying "Jonathan, I want you to decide whether we're having fish or steak for dinner - but if you pick steak, I'm going to force you to eat gravel instead." It might get you to pick steak, or you may stick with your choice of fish and see if you're really the sort of person who will force folks to eat gravel - and if you are, well, I'm sure glad I didn't pick you to make my dinner.
Regarding his tendency to poll better against Republicans than Clinton… that's true, but if you account for the amount of press coverage toward each, and past elections and how press there has worked, it seems as though Sander's strength comes from the fact he hasn't been attacked by Republicans yet.
Further complicating things, the Right's internal math says Clinton is more likely to win - and has their own
#nevertrump movement that says they'll vote for clinton over trump (not sanders though.)
So you've got Sanders predicted to win by some democrats, but only because he hasn't been slammed by republicans AND because his supporters are willing to throw the election if he doesn't get the nomination, and Clinton predicted to win by most democrats and most republicans, and there's no more dirt to throw on her - the odds there's some hidden scandal around her is real slim, while from a moderate/independent perspective, the amount of untouched scandal around Sanders is absurd.
On top of all of that, you're saying that Sanders will wait to pitch superdelegates until the convention is closer, which may be true for him and his campaign… but isn't true for many of his supporters. I'm, as you may know, tight with lots of political folk on both side of the aisle - I actually had dinner with an ex officio delegate a few nights ago, and he's actually disconnected his home phone because of the steady stream of threats he gets to vote for Sanders. Same for the other delegates I know in this state (bar one, who's known for being more to the left.)
So you're counting on Sanders' campaign being able to go up to people who have been harassed for months and going "If you don't vote for me, the harassment won't stop, and we'll let Republicans take control of the country."
And do you know what tends not to work very well on public officials? Vaguely threatening coercion when it's happening under incredible public scrutiny.
Put simply, the only strength Sanders can put forward to secure the nomination is the ability of his supporters to rally together and threaten low-level public officials.
You're relying on people who, at this point, personally dislike him for what they have done to the party they have worked to grow and strengthen for years, if not decades, to suddenly cave into the same threats they've been hearing for months now. It's not going to happen.