Londoners will face rising rail fares as the government announced services will not come under Sadiq Khan 's power.
Transport Secretary Chris Grayling rejected Sadiq Khan's plans to control rail services coming to the capital, saying he only wants Transport for London (TfL) to be "closely involved".
Despite former Transport Secretary Patrick McLoughlin assuring Londoners TfL would take control of suburban rail as each franchise came up for renewal, the decision has now been "formally rejected".
London Assembly members on Tuesday December 7 urged the Cabinet to rethink the decision, claiming it did not put train passengers first.
Mayor Khan argued: "The only proven way of improving services for passengers is giving control of suburban rail lines to TfL.
"This is why the government and previous Mayor published a joint prospectus earlier this year."
He added: "Anything short of this simply won't make the improvements desperately needed.
"It is a fact, TfL lines have more frequent trains, fewer delays and cancellations, more staff at stations and fares are frozen.
"We will keep pushing the government to deliver the rail devolution they have promised and that is needed."
The news comes as Mr Grayling faces calls for resignation after a leaked document to the Evening Standard from 2013 said the decision was to "keep suburban rail services out of the clutches of any future Labour Mayor".
Should the decision not be revoked, south central, southwest and north London services would not transfer to TfL until at least 2020.
There is cross party support for devolution from MPs, assembly members and councils inside and out of London, City Hall today (December 7) announced.
Assembly Members (AM) today agreed a unanimous motion calling for the Secretary of State to reconsider his decision not to devolve franchise management of Southeastern services.
A letter will also be written to Prime Minister Theresa May to express City Hall's views.
AM Len Duvall, who proposed the motion, said: "Services managed by TfL have some of the best performances in the country, whilst passengers on some London and south eastern suburban routes have experienced amongst the worst.
"We need to move beyond political point scoring and the Transport Secretary needs to devolve franchise management to TfL who have proven capable of running decent services.
"It’s time for the Prime Minister to intervene and make this happen."
Keep up to date with the latest news in west London via the free getwestlondon app.
You can even set it to receive push notifications for all the breaking news in your area.