Here are the key bits of the e-mail sent by Alan Milburn and Charles Clarke to all Labour MPs and peers:
As we all know the coming months are critical for Labour's future. After ten years in office we will need to demonstrate that we have the vision and the policies to successfully meet the future challenges faced by our country and the wider world.
Like many others in the PLP and the wider Party we believe that requires an open participatory debate.
There are some welcome signs that the debate is beginning to happen within Government, in various think-tanks and in contributions made by a range of colleagues. From our discussions with fellow MPs and Party members, however, we believe there is an enormous appetite for the debate to be taken forward and given more focus.
There will, of course, be many different points of view about the future direction we should take as a Party but we believe the critical thing is to develop an open process for ideas and views to be aired.
Many colleagues have suggested that such a process would provide the opportunity not just of addressing the Party - important though that is - but of engaging with the wider public.
To that end we have decided to launch a new initiative to promote debate in what we hope and intend will be an open and participative way.
We are inviting all Labour MPs to the launch event which will take place at 10.30am on Wednesday 28th February [it gives details of the location, in the City of London] ... all Labour colleagues from both the Commons and the Lords are most welcome to attend.
Charles Clarke MP and Alan Milburn MP