I am trying
1) to persuade him that GTAs are overworked and underpaid. This is easy.
2) to get him to do something about it - or at least, what we want him to do. This is slightly harder.
Meanwhile I am also trying to solve the GTA collective action problem between departments. (A poli sci way of saying, I am trying to get us organized to lobby at university level as well as just departmental level. We are at the heart of undergraduate teaching and that should be recognized more than at present.)