Practices that fail to work together could see patient numbers drop and their QIPP (Quality, Innovation, Productivity and Prevention) programme "fall apart".
Speaking at the NHS Alliance's annual conference in Manchester on Wednesday (30 November), Dr Hugh Reeve, Chair of the Cumbria Clinical Commissioning Group, said primary care providers will have to commence a radical transformation and start to work together under joint contracts.
"A co-ordinated approach to urgent care and managing long-term conditions (LTCs) is something that cannot be done by individual practices alone," Dr Reeve told MiP.
"If practices don't start to work together, they can "kiss goodbye" to QIPP success."
He told MiP that while he is not advocating practice mergers, small practices do not have the "right skill mix" to develop services alone.
Also speaking at the NHS Alliance conference, Professor Steve Field, Chairman of the NHS Future Forum, said the NHS had "lost the plot" over primary care provision.
He told delegates GPs should no longer tolerate the variation in access to care.
Dr Reeve warned those practices that choose not to integrate with other practices in their area that they may start to see their patient lists fall.
"This transformation needs to happen at pace – if we do not make changes now, they will be imposed on us," said Dr Reeve.