I don't think Bush and erudite have ever been used in the same sense until now.

Erudite is not a dirty word, it is just a word that has the wrong connotation for voters. It describes someone that posses or displays erudition - "extensive knowledge acquired chiefly from books : profound, recondite, or bookish learning" according to Merriam Webster. The majority of voters do not want someone who displays that. They want someone that voices their feelings and concerns, someone who talks like they talk but has charisma. They want a leader they can trust. Kerry looks like he is filling that role.