Private providers, not-for-profit health companies, and voluntary organisations could become full members of the NHS Confederation, if existing members support new proposals to bring the independent sector on board.
The confederation has launched its second member consultation to establish whether affiliate members should switch to become core members of the organisation.
Following a similar exercise in 2003, a majority of confederation members wanted to bring the independent sector on board, but in a compromise move, non-NHS bodies were given affiliate status.
They currently have their own members' forum, they are represented on the confederation's governing council, and they sit on some of its policy committees.
But the confederation says it can currently only represent affiliate members alongside core members where there is 'a shared agenda'.
It says it has established successful niche forums for different parts of the NHS, such as its foundation trust network, and acute trust forum, and now it is time to consider whether the organisation will be more effective with the independent sector fully represented alongside traditional members.
NHS Confederation chair Peter Mount said: 'We believe we can represent the specific views of independent providers of NHS services, and this would not be at the expense of how we represent NHS organisations currently.'
Five meetings will be held around the country to discuss the proposed change in membership, and the consultation closes on 5 April.