When a butterfly flutters in Springvale South can a sitting Prime Minister be ejected from the Lodge? That's the question Labor MPs are pondering this morning after Bill Shorten's 11th-hour press conference switching his personal support away from Julia Gillard and towards Kevin Rudd.

Right up until last night Shorten was holding on to his default position -- playing dead on the leadership, even as the state party moved around him, to avoid going down in history as the "faceless man" that knifed two prime ministers.