According to reports, eight shadow cabinet members have said they will quit the front bench if Mr Corbyn, the current frontrunner, is victorious when the result is announced on Saturday.
Already Blairite leadership candidate Liz Kendall, shadow home secretary Yvette Cooper, shadow chancellor Chris Leslie and shadow business secretary Chuka Ummuna have confirmed they would refuse to serve on the frontbench team of a Corbyn leadership.
Yesterday Mr Ummuna said that he “does not share the same values” as Mr Corbyn over unilateral nuclear disarmament, increasing national insurance, taxing businesses more and foreign policy.
But in a conciliatory gesture he added: “There are other ways to serve the cause.”
Other high-profile figures who will not serve in his top team are the current acting leader Harriet Harman who will retire from front bench politics along with former leader Ed Miliband, who quit after the election.
However, in a surprise move, it is understood former chief Treasury secretary Liam Byrne told a meeting of the parliamentary Labour party that he would be prepared to join a Corbyn shadow cabinet despite being from the right of the party.
However, with senior figures on the right and moderate wings of the party making it clear they will not stay in the frontbench team with Corbyn as leader, a senior figure in his campaign team told The Scotsman that they are doing the leftwinger’s work for him and opening the way for a hard left front bench.
He said: “They are doing Jeremy’s work for him. It saves him from having to try to sack them. It would be much more difficult if they stayed in the the shadow cabinet and tried to influence policy. But they don’t see that.”
The comments came amid reports that Mr Corbyn, who only joined the contest “to widen the debate”, has been asked to quit the race for the good of the party.
He is said to have replied that it had “gone too far” for him to do that.
A source in the Corbyn camp added: “It is a different party now. This campaign has changed things. People keep saying it is the union leaders but this is a grassroots movement.
“People like [Unite general secretary] Len McCluskey are being pushed by their membership into backing Jeremy.”
He admitted that it was still uncertain whether Mr Corbyn would win but added: “I would bet my mortgage on it if I could.”
Meanwhile, Prime Minister David Cameron has paid tribute to Ms Harman as she took part in Prime Minister’s questions for the last time yesterday.
He said she has been a “robust adversary” in the House of Commons, and that she was a “fierce champion” for her constituents.
Voting in the leadership contest is due to close today with the winner announced on Saturday morning.