The candidates for the leadership should be pushed to come to an agreement to stand by Labour Party policies as these have been (and will come to be) agreed by Labour Party Conference. This does not unreasonably bind them. They should still be free to suggest changes that they would like to seek in future Conference's policies, whilst sticking by what has been established in the meantime. Furthermore leaders and the PLP can still have a say about the priorities, timing and the detail when acting on Conference decisions. They will also often have to act on new and passing items, without having specific Conference guidance at the time. This is currently the case (until the coming Conference ?) on policies over leaving the EU.
Most of current Conference policies formed the basis of our last election manifesto. Any alterations, additions or elaborations (e.g. on Syria) have only emerged so far from last year's Conference. Most of Conference policies arise (of course) from the work of the Policy Forums. Prior to the General Election, I summarised these in a number of blog items. These can be found via links in this item. These proposals should form the basis of Labour"s current parliamentary approach, until subject to later Conference alterations.
It is also possible for candidates to press for the further democratisation of the Labour Party. It is also a difficult approach for candidates to argue against when facing the votes of the membership in a leadership contest.
I hope that Labour Party members will push such a line. It could be a position which any candidate could find it difficult to reject in current circumstances.