The GOP promised Ted the world if he would go along with their "anyone but Trump" narrative. Hence all the endorsements and backing. However they never had any intention of allowing Ted to be the nominee. They are continuing to use Ted, who seems only to willing to go along with it thinking it might lessen the damage done to him if he can blame someone else for what he has done.
It could also be that he is promised, in a few years, after the heat dies down they will do him some political favours so his career is not totally destroyed.