Plans to give mayor Ken Livingstone powers over local rail services outside London have been unveiled.
The mayor could pay for additional services
The public is being consulted on the proposals which could give the mayor a say on services as far out as Sevenoaks in Kent and Epsom, Surrey.
Mr Livingstone would not have input on intercity services.
The government said there was a case for change as a number of inner London services begin or end just outside the Greater London Authority boundary.
The Department for Transport (DfT) outlined the plans in a consultation programme on Thursday.
Rail Minister Derek Twigg said: "Our aim is to secure better integration both on the railway and with other modes of transport."
Mr Livingstone's powers could include paying for additional train services and different stopping patterns.
He could also propose reductions to services and redistribute the savings elsewhere.
Any new arrangements would have to properly represent the interests of travellers and others outside of London, the DfT said.
Any powers given to the mayor would be subject to the government's approval.