Labour's deputy leader Angela Rayner has claimed Sir Keir Starmer's bid to end the one-member-one vote election system won't be voted on at party conference.
This is despite Labour apparently confirming the party leader would be putting his reforms for electing future leaders to the party's National Executive Committee (NEC).
Matt Wrack, general secretary of the Fire Brigades Union (FBU), said it would be a 'bit rushed' for the Labour leader to bring his party reforms to the autumn conference.
Ms Rayner told the BBC's Today Programme there would be no vote this weekend, but it was likely to be discussed.
Meanwhile, left-wing campaign group Momentum said proposals to bring back Labour's electoral college are 'dead'.
Sir Keir Starmer's (pictured) reforms to the way party leaders are elected are not going to be voted on at the Labour party's conference this weekend
Ms Rayner said: 'Conference is a time when we discuss rules. These are things conference does every year.'
But at a meeting planned for today Ms Rayner said the proposed changes were not on the order paper. She added: 'My understanding is the electoral college is not coming to the NEC. What you will hear is a hell of a lot about how we will fix this country.'
When pressed on whether she supported Sir Keir's plan she added: 'There isn’t a proposal coming forward so I can't say whether I support it or not.'
Mr Wrack, a trade union leader who was part of a Trade Union and Labour Party Liaison Organisation (Tulo) meeting this week to discuss the proposals with Sir Keir, told BBC Radio 4's Today programme conference wasn't the place for discussions around the election of party leader.
He said: 'I think the first thing to say is what do people want out of Labour conference? We've got a jobs crisis coming up, a living standards crisis coming, energy crisis and so on.
'If Labour is going to win power and take on the Tories, I think people need to see Labour standing up for working people and that's what we want, and I'm sure that's what Labour voters want to hear - not a debate around how we elect a leader or select Labour MPs, and obviously how that will engage people wondering who to vote for.
Labour Party deputy leader Angela Rayner (pictured) told the BBC's Today Programme there would be no vote this weekend, but it was likely to be discussed
'The conference starts today, so it seems a bit rushed to try and bring major proposals about the constitution of the Labour Party in a morning.'
Mish Rahman, a member of Labour's NEC and Momentum's national co-ordinating group, said: 'The central measure of Keir Starmer's attack on democracy has comprehensively failed. The electoral college is dead.
'Now to make sure all the other regressive rule changes concocted by the leadership share the same fate.
'From trigger ballot changes to increases in the MP nomination threshold ahead, they all need to go in the bin. Starmer won't stop trying to rig democracy, so we can't stop defending it.'
Ms Rayner said she had been told proposals to bring back an electoral college are not on the agenda for the NEC meeting on Saturday.
Speaking to BBC Radio 4's Today programme, she said: 'We've got an NEC meeting later today.
'I'm told that the electoral college is not on the order paper for the NEC - I haven't seen it because I got up at 5am this morning to speak to all of you in the media.
'But, you know what, that is not uncommon.'
Asked whether leader Sir Keir Starmer's proposals were likely to be voted on at conference, Ms Rayner added: 'Some will, some won't
