In order for Kanemichi to accomplish the above, he needed to have MINAMOTO no Kaneakira return to the Imperial family, (at that time there was a custom that the Imperial family was not allowed to become Sadaijin) and promote Yoritada as his successor.
そのためには現職左大臣であった元皇族の源兼明を皇族に戻して（当時、左大臣は皇族が就けない慣習であった）頼忠をその後任として昇格させる必要があった。