Speaking for the GMB general union, Dick Pickering said proportional representation, and the supplementary vote system narrowly recommended by the Plant working party on electoral systems earlier this year, was about losers - 'those who seek to dilute our policies'.
Urging conference to endorse John Smith's commitment to hold a referendum on whether the first-past-the-post system should be scrapped, Larry Whitty, the party's general secretary, said: 'Give the people the right to decide on their own form of democracy.'
Mr Smith is against change, and the rest of the party deeply divided. What ought to have been a high-profile and well-attended debate fell victim - like defence - to conference management difficulties, however, with only half the session completed last night to a half-empty hall.
That means hundreds of delegates voting today would have heard only half the speakers. Despite opposition from the entire Transport and General Workers' Union delegation, however, the resolution is expected to be narrowly passed.
The main planks of the PR campaign's case are that first-past-the-post is fundamentally undemocratic and consistently returns Tory governments on a minority of the vote.
Charlie Simmons, from Sheffield Hillsborough Constituency Labour Party, said: 'It's no good electing Labour MP after Labour MP when we have a voting system which returns Tory government after Tory government on a minority vote which closes our pits, destroys our steel industries, abolishes wages councils and imposes the poll tax.
'We need to make the connection between what has happened over the last 14 years and the electoral system that allowed them to get away with it.'
Pro-PR campaigners accept that to make the change Labour must first win an election under first-past-the-post. It is at that point that the referendum, if endorsed as party policy today, would be held.
Mr Simmons said: 'I do believe we can win the next election under the present system and indeed I think we will. But people out there need more than one Labour government every generation.'
While proportional representation systems can be designed to ensure extremist parties do not benefit unduly, the more common charge that PR would benefit the Liberal Democrats, and increase the chances of a hung Parliament, remains powerful.
Paul Tyler, of Woolwich CLP in south-east London, said: 'Promoting PR is tantamount to tearing up election promises.'