What two boys tried to convince Ralph to stay chief?

Piggy and Simon both encourage Ralph to remain chief.
Toward the end of chapter 5, Jack says, "Bollocks to the rules!" as his group of hunters exit the assembly meeting (Golding, 130). Ralph immediately becomes upset and depressed at the entire situation. Ralph is well aware that Jack is slowly gaining power, and he cannot stop him. Ralph then says that he should give up being chief. However, Piggy and Simon disagree with Ralph's assessment of himself, and both encourage him to remain chief. Piggy tells Ralph that if he relinquishes his authority, Jack will become chief and ruin the boys' chances of rescue. Piggy also mentions that he is scared of what Jack would do if he were to become chief. Simon also encourages Ralph to remain chief by saying,

Go on being chief (Golding, 132).

Piggy then tells Ralph that Jack cannot hurt him and will hurt the next thing, which is him. Simon once again displays his support for Ralph by saying,

Piggy’s right, Ralph. There’s you and Jack. Go on being chief (Golding, 133).

Out of all the boys on the island, Piggy and Simon are Ralph's biggest supporters and refuse to follow Jack and his tribe of savages.