Why is Ralph considering giving up his position as chief?

Ralph considers giving up his position because the things he hoped to accomplish have not come to fruition. He doesn't believe himself intelligent enough and cannot inspire the other boys to help get the things done that need to be done. He's frustrated over the entire situation, as well as saddened by his own unkempt appearance. Even after calling a meeting, Ralph's words are lost as a result of Jack's interruptions. Jack has the stronger personality, but he has the wrong priorities.