John McDonnell has accused Keir Starmer of a ‘grubby’ and ‘dishonest’ approach over his plans to reverse the one-person-one-vote system for leadership elections.

The party has used this system for leadership elections since Ed Miliband’s 2015 reforms, which were largely seen as responsible for moving the party to the left under Jeremy Corbyn.

Restoration of the prior system would give the Parliamentary Labour Party (PLP) one-third of the votes in leadership elections, with the party membership and unions receiving the other two-thirds of the votes.

There are also plans to increase the barriers to local parties deselecting MPs.

The former shadow chancellor John McDonnell told BBC Radio 4 on Wednesday that he believed the Labour leader’s plans were “a huge mistake”.

He said that concentrating on “internal factional disputes” is not what people expected at Starmer’s inaugural conference, the first in-person conference since the pandemic.

He emphasised that Starmer “was only elected 18 months ago” and argued that he “is opening himself up to charges of dishonesty on this.”

He said that “a proper consultation” must occur before any changes are proposed.

He went on: “Look at the contrast there is going to be in the media, you have Boris Johnson strutting the world stage, doing deals with Biden and other world leaders, trying to prepare for COP, and what do we have, the Labour leader in grubby stitch up deals, trying to bounce his own conference. It is unacceptable.”

Responding to Starmer’s plans to toughen the deselection process he said, “It is fundamental to democracy that our members should decide who should represent them in Parliament. We reached a compromise position, a de-selection procedure, a few years ago.

“After this Labour Party conference, we could be within 18 months of a general election, are we going to spend at least half of this conference coming up, addressing internal matters like this, and having factional disputes that spill over for the next 6 to 12 months?”

Labour MP Ben Bradshaw complained via Twitter that McDonnell was permitted to “attack” Starmer, alleging that no official Labour spokesperson was invited onto the program to defend his plans.

Fellow Labour MP John Spellar also expressed support for the proposals, responding to a tweet by highlighting that “Tony Benn and CLPD backed the electoral College”.

Starmer outlined the proposals to his shadow cabinet on Tuesday, saying: “Our rules as they are right now focus us inwards to spend too much time talking to and about ourselves and they weaken the link with our unions. I know that this is difficult – change always is – but I think these changes are vital for our party’s future.”

“These are two things that have got to change if we are serious about winning the next election.”

Sharon Graham, general secretary of Unite, the second-largest trade union in the UK, who released a statement criticising the plans on Tuesday, has confirmed that she will not be attending the conference. In a statement via Twitter, she said: “My priority is Jobs, Pay and Conditions. I will be standing on picket lines with @unitetheunion members rather than sitting at a conference.”

Former party leader Jeremy Corbyn also hit out at the proposals via Twitter yesterday, stating: “It’s time to stop attacking Labour members’ democratic rights – and take the fight to the Tories”.