He has made no secret of the fact he wants to take over every rail service in London -- and today the government appeared to back Boris Johnson's plans.
The Transport Secretary Patrick McCloughlin told London Tonight he had 'no objection in principal', to the Mayor of London having power over rail franchises.
He pledged his support as Mr Johnson officially opened a new route on the London overground service.
Our Political Correspondent Simon Harris has the story.
More top news
Police are hunting for the owners of this jewellery which they believe is stolen
Police investigating the murder of a 20-year-old man in East London have named him as Moosakhan Nasiri.
18 year old Shafiq Smith was charged early this morning with the murder of Omid Saidy