Jeremy Corbyn has issued a rallying call for Labour MPs to "unite, cherish and build our movement" as expectations rise of his all but certain victory in the battle to retain the party leadership.

The veteran left-winger is hot favourite to see off the challenge from rival Owen Smith when the results of the leadership election are announced in Liverpool on Saturday, with bookmaker William Hill giving him a 99 per cent chance of success and an odds-on hope of improving on the 59.5 per cent support he received when first elected a year ago.

In an end of campaign video message to supporters, he said that internal critics had a "duty to unite", regardless of the margin of victory.

But senior moderate Caroline Flint said that Mr Corbyn needed to show he could listen to internal critics if he was to bring the party together and she warned of "warfare" if he allowed talk of MP deselections to continue.

After private talks this week with senior MPs on Labour's moderate wing, the Islington MP is expected to seek to rebuild his frontbench team in the wake of the expected confirmation of his position.

The resignation of more than 40 frontbenchers in June left him unable to fill all his shadow ministerial posts and reports have suggested that as many as 14 might be ready to return following the apparent failure of Mr Smith's bid to unseat him.

But others, including senior figures Hilary Benn, Yvette Cooper and Chuka Umunna are thought likely to focus on their bids to secure the chairmanships of influential parliamentary committees, which will allow them to take prominent roles scrutinising Theresa May's government from outside Mr Corbyn's camp.

Labour's ruling National Executive Committee was due to meet after the result is announced, after putting off a decision earlier this week on proposals to restore elections to the shadow cabinet, which might have given some centrist MPs a route back into Mr Corbyn's top team.

It was not clear whether the issue will be settled over the course of the coming week's annual conference in Liverpool, with Mr Corbyn preferring a wider review of Labour's democratic structures to give more decision-making power to the membership.

In his video message, Mr Corbyn said: "This isn't and never has been about me. It's about all of us. Whatever the result, whatever the margin, we all have a duty to unite, cherish and build out movement."

Rejecting the claims of critics that he is more interested in consolidating the left's hold over Labour than in winning power, the party leader insisted that the wave of enthusiasm which drove his second leadership campaign - just a year after he was first elected - would boost the party's hopes in the general election scheduled for 2020.

With 40,000 volunteers signing up to take part in his leadership campaign and membership numbers swelling to more than half a million, Mr Corbyn said Labour would be able to deliver "a new kind of general election campaign - the biggest, best and most visible we have ever run".

Admitting that the leadership contest had been "robust and at times difficult", he insisted the debate had nonetheless been "respectful" and the party was agreed on key issues like opposing austerity.

"Now let's turn our agreement into unity, our passion into action and our ideas into reality," he said. "We must win the next general election so Labour can rebuild and transform Britain so no-one and no community is left behind. We can and must do that together."

The scale of Labour's challenge was laid bare by a poll suggesting that more than half its supporters who voted to leave the European Union could now back other parties at a general election.

The YouGov survey showed just 48 per cent of 2015 Labour voters who backed Brexit would continue to support the party, while nine per cent would switch to Tories and eight per cent go to Ukip. A quarter said they were unsure what they would do.

On overall voting intentions, the snapshot put the Conservatives on 39 points and Labour on 30. Ukip polled 13 while the Lib Dems polled just eight in the wake of their conference at the weekend.