Sources said the party’s ruling body was ready to accept a compromise deal on the so-called McDonnell amendment, named after the shadow chancellor, who is in favour of reducing the number of MPs needed to nominate a leadership candidate.
The NEC will vote on the idea of reducing the threshold from 15% of MPs and MEPs to 10% in order to select candidates to be placed on a ballot for members.
That would open up a future leadership race to a significant number of new potential candidates, who may have struggled under the current rules, but does not go as far as the 5% demanded by some activists.
When Corbyn stood for the party leadership in 2015 he struggled to secure enough nominations, and only made it through to the membership ballot because some MPs said they would second him even though they were not his supporters.
One source suggested there could also be an agreement for five new members being added to the committee to represent trade unions and the party’s membership. That would tip the balance of power on the key grouping further towards Corbyn.
One source close to the NEC said the reforms were ones both moderates and pro-Corbyn members would be likely to support - and said more places on the NEC for members would not necessarily guarantee that the party’s left would control the committee for ever.
“Things can change quickly and you can’t guarantee that members who are elected will be of a certain political persuasion forever; it’s short-sighted if that’s what you’re banking on,” the source said.
Key figures who have previously been seen as potential obstacles to reform by the leadership, such as the party’s deputy leader, Tom Watson, are likely to back the compromise reforms.
With the NEC’s backing, the changes are highly likely to pass a vote on the conference floor. On Tuesday, the NEC is also likely to agree a sharp rise in the number of all-women shortlists ahead of snap candidate selections for the next general elections.
Sources hailed this as a huge step towards a gender balanced party, but is likely to mean some male candidates who stood for the party in June and did not win seats will not get a chance to stand for the nomination again.
The meeting will also see the conclusions of a leak inquiry into how the party’s manifesto ended up in the hand of journalists during this year’s snap election. Sources said the conclusion was that it was not a parliamentarian who was guilty of the leak, and it was someone outside of London, although nobody is expected to be named.
A source from Momentum, the leftwing grassroots group that has supported Corbyn, said: “[We] hope the NEC meeting tomorrow will take account of this grassroots desire to make the party more democratic and give members the chance to debate the issues they care about at conference.”
But Richard Angell, director of the centrist pressure group Progress, questioned the need to push for the rule changes.
“When the current leadership is so safe at the top of the party, it is bizarre the focus of this year’s conference is divisive rule changes about whoever succeeds Corbyn, whenever that might be. Allowing nine or more candidates in the ballot paper threatens to make a joke of Labour and put us further from the voters,” he said.
He also argued that while it was understandable that members wanted more of a say on the NEC, the group ought to be regionalised or it would simply amount to a bigger voice for London and the south-east.
He added: “This package is all about marginalising Labour MPs in the Labour movement. Reducing the importance of MPs is the worst way of convincing the public they should elect more of them to bring about a future Labour government.”
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