In the context of medieval Europe, let's say a pretender to a throne deposes a sitting monarch. Not only does he have the backing of sizeable number of nobles but is also acceptable to the burghers of the major cities. The top clerical authority of the realm, however, refuses to crown the pretender as king. What happens now? Does the pretender and everyone else simply ignore the fact that there was no coronation? Can this de facto king appeal to the Pope to overrule the opposition of the local clerical authority?