Mr Lansley writes that his proposals are not about 'overburdening you with paperwork or involving you in the minutiae of administration'.
Instead, the reforms aim to give GPs 'overall responsibility for the design of services which meet your patients' needs, and to respond quickly when failures in those services arise'.
Many GPs will have been frustrated by poor commissioning in the past, Mr Lansley writes. 'This is why I believe you are best placed to make every penny count in the NHS, for the patients it serves,' his letter says.
The letter also tells GPs that they should 'not feel under pressure to form working arrangements at this stage'.
He re-emphasises that consortia will determine their own size and structure, with central guidance kept to a minimum. 'Only essential duties' will be set out as statutory responsibilities of consortia, he writes.
Mr Lansley adds that these duties will be clarified after the consultation and the health bill go through parliament.
He asks GPs to start considering who they would like to work with, what services they feel are appropriate to commission themselves and where they might want support.