Maybe Trump could try the Bolsonaro maneuver: don't go to debates.It's rare for me to side with the elderly socialist, but unless the DNC fucks him over like they did last time, Bernie seems likely to win the nomination. This is a good thing for the dems, as he is the least failure-prone candidate on their roster. Not to mention the one person within a shot to take down Trump in a debate.
It worked for him but, on the other hand, Trump can talk to a crowd, something Bolsonaro can't.