I guess the lesson is that if you want to prove that you are an authentic, left leaning candidate for office then you invite Sanders in to give you backing, knowing full well that this gesture may well cost you the seat. The flip side is that you can feel good about losing.
Some people don’t run for election in order to win, they do it to educate. Winning means having to be compromised. This is the dilemma that British Labour part members have. They love Jeremy Corbyn to bits and almost couldn’t give a sod that they will lose big time. Losing big time is great because it means Labour is being true to its grounding principles.
Of course everyone dreams of winning despite all this, but there’s little patience now for winning pragmatically. Politics has done a major U Turn.