Moves to give London mayor Ken Livingstone more powers over local rail services have been announced.
Fares and tickets across London transport could be "rationalised"
The mayor, who runs buses, trams and the Tube would get responsibility for trains in greater London under White Paper proposals published on Thursday.
In future, the mayor may be able to "buy in" additional services on crowded routes or make savings on others.
While private companies would still run services, the mayor would have a say on areas such as fares and ticket systems.
It could mean Transport for London (TfL) paying train operators a fixed fee in return for collecting fares.
BBC London's transport correspondent Andrew Winstanley said that way, London's transport budget would benefit from any upturn in passengers.
Announcing the proposals, Transport Secretary Alistair Darling said: "London's public transport system is one of the most extensive and complex networks in the world.
"Greater integration between the rail, bus and underground networks could bring enormous benefits to the millions of passengers that use them everyday. "
Mr Livingstone, who has spent millions on London's bus network and the £5-a-day congestion charge, welcomed the announcement.
The Silverlink Metro service is among routes he wants to upgrade.
He said: "Given the North London Line is the most overcrowded line in Britain, we would want to take immediate action to increase the number of trains and, as soon as possible, bring in new and longer trains."
TfL body says it will work with the government to make the White Paper proposals deliver benefits for passengers as soon as possible.
Ian Hall, a TfL managing director, said: "These benefits include the rationalising of fares and ticketing through the extension of the successful Oyster card scheme.
"In addition, we would work hard to improve reliability, safety and accessibility of services and stations."
But the announcement attracted criticism from Mr Livingstone's political rivals.
Tim Yeo, Conservative transport spokesman, asked Mr Darling: "Why on earth do you think that putting Ken Livingstone in charge of trains is a good idea?"