Ken Livingstone hit out at Boris Johnson this morning, describing him as a 'do-nothing Mayor'. He said: "With the exception of this rather silly little cable car there's nothing else he has started. If we have another four years like that then by the end of this decade London will be insufferable."
Boris Johnson said he would "definitively, categorically, emphatically" turn down the job of Prime Minister if it was offered to him.
So what challenges await the man tipped by many to one challenge for the leadership of the Tory party?
With defeat at the polls Ken Livingstone, a colourful political figure for over 40 years, has stepped down.