Why does Piggy desperately want Ralph to stay on as chief?

Piggy desperately needs Ralph as a friend and a chief. Ralph is trying to hold these boys together but they keep drifting towards chaos and violence. This Darwinian environment doesn't work well for guys like Piggy. Ralph offers a shred of hope that Piggy can survive if not get rescued. Under Jack's rule, Piggy is finished. Piggy's strengths are, too many of the boys, are his weaknesses. As the novel progresses, Ralph appreciates Piggy more and more.