Labour grandee, Baron (David) Blunkett of Hillsborough, has warned the chances of peace between Jeremy Corbyn and the majority of his MPs appears "miniscule" if – as expected – he is re-elected as party leader. He also questioned whether compromise was possible.

"The outcome of the Labour leadership ballot, and the implications for British politics, is a concern for all those who hold democracy dear and want not just an effective opposition but a real choice for the electorate over who governs Britain," he wrote in the Yorkshire Post.

Corbyn is expected to be elected with an even bigger mandate from grassroots activists than when he first won the leadership in September 2015. He is expected to hold a series of meetings with the party's MPs once the result is confirmed.

Voter turnout was rumoured to be around the 77% mark.

In a video message, he said that critics have a "duty to unite", regardless of who wins and how big the victory is, insisting that the enthusiasm triggered by the second leadership campaign would boost the party's chances in the next general election in 2020.

With membership numbers at more than half a million and 40,000 volunteers signing up to take part in his campaign, Corbyn said Labour would deliver a "new kind" of general election campaign.

His shadow chancellor John McDonnell told the Mirror they were planning a "tea offensive" to persuade the rebels to come back.

"We will be talking to as many people as possible, saying to people 'let's have a cup of tea' and can we try not to communicate by Twitter, it's not the most constructive way of communicating, so let's have a cup of tea and sit down and that will go on intensively over the next couple of weeks," he said.

But Lord Blunkett questioned whether a "clean slate" was possible.

"If it meant removing the threat to Labour MPs and finding a formula what would allow stability and security in the light of boundary changes, this would go a long way to allowing some sort of peace to break out," the former Home Secretary wrote.

But he said the chances of this were "minuscule".

"It is not only that the Corbynistas want to replace what they see as the 'old guard', but that they actually blame Labour MPs for any drop in the opinion polls," he wrote.

"In simple terms, when the polls drop, when by-elections at local level are lost as they were in Sheffield earlier this month, it is not the fault of the leader but rather those who have undermined him."