John McDonnell: It will be ‘tough’ for Jeremy Corbyn to win leadership contest with same margin as 2015

'Let’s be honest, we’ve got problems in terms of what will happen on Saturday'

John McDonnell arrives at campaign rally in London on 20 September (AFP)

Shadow chancellor John McDonnell has told supporters that it would be “really tough” for Jeremy Corbyn do as well as he did in 2015 – but warned critics it would not dilute his authority.

Speaking to activists in Clapham, Mr McDonnell, chair of Mr Corbyn’s leadership campaign, said he expected his long-time ally to win the contest but also attacked opponents for shutting supporters out of the contest.

His comments came as voting in the leadership contest came to a close on Wednesday.

Mr McDonnell said: “On Saturday – let me be straight with you – I think it’s going to be really tough to get the 59.5 per cent that we got last time around because of the numbers that have been prevented from voting… some will argue if we dip below the 59.9 per cent that somehow Jeremy’s mandate has lessened. If we win, no matter what, his mandate is still in place."

His comments, however, could either be a form of expectation mangement - designed to make the results appear better than predicted on Saturday - or a genuine reflection of private polling carried out by the Labour leader's office. Sources in Owen Smith's camp have also told The Independent they expect the result to be much closer than what has been suggested by public polls.

Mr McDonnell, the MP for Hayes and Harlington, also used his speech to attack a decision made by Labour's ruling body, the NEC, to prevent new supporters from voting in the contest by adding a "freeze date" for signing up.

“Let’s be honest, we’ve got problems in terms of what will happen on Saturday," he added. "The ruling out of 130,000 members was a disgrace to be honest – an absolute disgrace. And the way it was done was even more disgraceful at the end of an NEC when people had left… it was 14 people preventing 130,000 people having a vote.

“So we lost a large group of people who were Jeremy Corbyn supporters. I think never again should we allow that to happen.”

The shadow chancellor also told supporters he thought it was incumbent on all members of the party to come together and start preparing “very rapidly” for a general election. He said: "The message needs to go out to all party members and all those in the parliamentary Labour party [PLP] now, is unity - we unite behind the leader.

“There are members of the PLP already contacting us saying they want to serve, they want to hold position, and I am really grateful for that.

"There will be some who will not want to do that, and what we have got to do as a movement now is to emphasise that unity, that message all the way through, and then prepare for a general election."

He added: “The most important thing on Saturday - accept the mandate, respect the will of our members, unite, and then start preparing for that general election, and on that basis I think we can win an election and start transforming our country.”