Eugene IV is elected pope. An Augustinian monk and a nephew of Pope Gregory XII, Eugene IV is picked for the papacy because the cardinals hope he will treat them less as servants of the papacy and more as partners when it comes to matters like administration, theology, and doctrine. The cardinals won't get what they re looking for, though.
Pope Eugene IV is a firm believer in the doctrine of papal supremacy. Because he handles people so badly, church delegates at the Council of Basel (which Eugene will try to dismiss, but he'll be ignored) depose Eugene IV and electe Amadeus VIII, duke of Savoy, as Antipope Felix V.