The Transport and General Workers' Union, in its motion for the Brighton conference, rejected 'any proposals which would weaken the relationship between the party and the unions'. It condemned any suggestion of curtailing union input into the decision-making procedures of the party.
In less strident terms, the motion of the GMB general union called for the one member, one vote (Omov) principle to be extended to those who supported the party through payment of the political levy.
On Wednesday, Mr Smith secured the approval of a review group of MPs and union leaders for a modified package which is expected to be endorsed on Monday by the National Executive Committee.
Under the 'consensus' plan, election of the party leader and deputy would be by an electoral college in which party members, MPs, and unions would have an equal say.
Selection of parliamentary candidates is the more controversial area, with Mr Smith sticking to the Omov principle, though with the option of widening the franchise to union members who pay the political levy and are prepared to pay an extra fee to register as Labour supporters.
The TGWU and GMB together hold 18 per cent of conference votes. The GMB's motion leaves room for manoeuvre before October, though Mr Smith would have to drop his resistance to further compromise.
The Labour leader's main hope rests on winning the backing of medium-sized affiliates such as the shop workers' union, Usdaw, and the public service workers.Reuse content