Seeking approval of their enemies, particularly their media enemies. Many incumbents start craving to have everyone love them and no one hate them. But trying to make friends of their enemies makes enemies of their friends. Failure to handle constituent relations effectively. All politics is personal.
Service can be as important to voters as policy.
They appreciate prompt personal service when they contact those elected to serve them. Succumbing to temptations newly present when one achieves some power. Election to office tests anyone's strength of character, family ties and personal morality. Getting greedy for money or higher office. Many people, constituents who request help and especially the officials' staff, treat incumbents with deference bordering on obsequiousness.