The first draft of the mayor's London Plan, or spatial development strategy, will be published in a couple of weeks.
There are fears the draft, which sets out an all-encompassing vision for the next 15 years, will ride roughshod over London boroughs and be too bureaucratic.
A spokesman for the Association of London Government said the plan would need to be 'coherent' and provide a 'framework for detailed action by the boroughs'.
Labour planning spokesman John Biggs said the plan must be 'lean and strategic'.
He said: 'There was something called a greater London development plan, under the Greater London Council, which was widely viewed as so bureaucratic that it never saw the light of day.'
It was too early to say if this plan would avoid that trap: 'One gets different messages out of the Greater London Authority woodwork.'
Another burning issue is how the London mayor will ensure developers build a percentage of affordable housing.
The problem is particularly complex in inner London, where boroughs can make huge profits from luxury developments.
Bob Neill (Con), chair of the planning and spatial development committee, said: 'This will be a test of Ken Livingstone's credibility to see how flexible he is according to what [the assembly] has said.'
The assembly is far from united. The Conservative group is concerned developers will be put off building houses because of demands for affordable housing. They have also attacked what they see as an anti-car bias in the plan.