Last month, the GPC and RCGP both said consortia covering less than 500,000 people would struggle to manage financial risk. But data from 93 PCTs obtained under the Freedom of Information Act show some GPs are looking to create far smaller groups.
Responses also revealed that GPs in 78 of the PCTs that responded are yet to make even tentative plans about future consortia structures.
Some areas are looking to build on existing practice-based commissioning (PBC) groups to form consortia.
NHS Salford said it was looking to 'maintain and develop' current arrangements. The area currently has one PBC group covering 242,000 patients.
Dr Brian Hope, a GP and medical director at NHS Salford, said: 'The area is recognised nationally as being "significantly advanced" in its PBC arrangements.' He said it was vital to build on the PBC group's successes, such as close links with the local council.
GPs in NHS Sefton expect two existing PBC groups to be maintained under future arrangements. The groups cover 155,000 and 120,000 people, although a PCT spokesman said this may change.
In other areas, plans are emerging of GPs looking to form larger consortia.
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GPs in NHS Tees plan to form a consortium to cover 567,000 people. In NHS Bromley, Greater London, a group could cover 324,900 people.
GPC deputy chairman Dr Richard Vautrey said it was likely that a 'variety of models' will emerge depending on local health economies.
'It is probably right that eight out of 10 have not made plans,'