But, while repeating that Labour must take its key decisions by one-member one-vote, he made clear there might still be a formal voice - possibly through a split block vote - for affiliated organisations such as the trade unions.
Speaking on BBC television's On the Record programme, he said: 'I think we will have one- member one-vote for all our key decisions, but we have to find a way in which that one-member one-vote is consistent with organisations being part of the party.'
The block vote's characteristic was that all the votes went in one direction, Mr Smith said. 'You have an internal view that might be narrowly carried, and all the votes go in that direction. I think that is a difficult principle to maintain in one-member one- vote, but I am confident we can find ways round it.'
Mr Smith's view - which looks potentially reconcilable with strong advocates of the union link such as John Prescott, the deputy leadership contender - came as he said that Labour would stand by redistributive taxation. 'I think there will have to be some element of redistribution in any fair tax system in this country.'
He added: 'If radical change involves the Labour Party subverting its principles and aborting its mission, then I'm a conservative in that very narrow sense - I don't want to abort our mission.'
There were, however, ways other than redistribution to help the least well-off - for example providing child care and training for single parents to help them earn and pay taxes. In his interview, he appeared to move a step nearer to Paddy Ashdown, the Liberal Democrat leader, in saying there was 'a distinct possibility' of having an independent chairman for the Commission on Social Justice that Mr Smith has proposed to produce a 'new Beveridge' on tax and benefits.
He would not raise objections to the Liberal Democrats being involved, he said, and the commission 'should not be the property of one political party'. While it would 'come from the Labour Party' it could involve people from other parties or none.
Mr Ashdown, who renewed his call for a 'new pluralism' producing a 'co-operative as well as competitive approach to politics' in a speech to party councillors at Eastbourne yesterday, has said any such joint commission should be independent of all parties.