It will never happen. Have you listened to him? Even though he has many of the same issues as Trump, but with disasterous "solutions", he despises Trump. It's pathological, a fellow New Yorker who cannot stand that Mr. Trump has spent his whole life being productive, earning billionaire status, while Sanders spent his whole lazy life bein' cool and finding a way to get a government check. You really think he wants to permanently change his lazy and comfortable lifestyle to lead a movement? Won't happen.
Can Sanders supporters sue him for fraud?
You’re right.
He also seems tired, and kind of over it, just as Trump said yesterday. How could anyone honestly have expected him to endure the stresses of leading the free world???