Labour is set to announce the name of its candidate for London mayor, in the first of a string of election results which will on Saturday reveal the identities of the party's new leader and deputy leader.
Former Olympic minister Tessa Jowell and human rights lawyer Sadiq Khan are believed to be frontrunners in the race for the right to represent Labour in next year's battle to replace Boris Johnson at City Hall.
But the nomination of a mayoral candidate is certain to be overshadowed by Saturday's announcement of a new leader, with polls and bookies both pointing to victory for left-winger Jeremy Corbyn,
The Islington North MP has confirmed that he has already started sounding out fellow MPs over posts in his frontbench team, and has names in mind for the key roles of shadow chancellor and shadow foreign secretary.
Speaking at his 99th and final public meeting of the four-month campaign, Mr Corbyn said he was "extremely confident" of being able to form a shadow cabinet. "I've had many discussions with people already about how we are going to take these things forward," he said.
Pressed over whether he had people in mind for the most senior posts like shadow chancellor and shadow foreign secretary, he told Channel 4 News: "Of course. There's lots of things in my head, including that."
Effectively conceding defeat, Blairite candidate Liz Kendall ruled out serving in Mr Corbyn's team, predicting the veteran campaigner would consign Labour to opposition.
"The programme Jeremy Corbyn offers is not new. His policies and politics are the same now as they were in the 1980s – and will end up delivering the same result," said Ms Kendall.
Mr Corbyn acknowledged that many Labour MPs do not back his agenda: "I've had many discussions with colleagues in Parliament over the past few days. There are many there who do not agree with many of the ideas I've put forward. I fully understand that.
"They also understand that whoever is elected leader - and we don't know who it's going to be - has a mandate that has come from the widest franchise there's ever been for a Labour Party election. So there's going to have to be some quite serious discussions about the way we do our economic policy and a number of other things."
He insisted he will remain "a normal human being" if he wins on Saturday, and hinted he may reject some of the trappings of the office of leader of Her Majesty's Official Opposition, such as Special Branch security, a £135,000 salary and a car.
"All those things are up for discussion on Sunday," said the famously frugal 66-year-old cyclist. "Do we get Special Branch bicycles?"
All of Labour's members, affiliated supporters and registered supporters in London were entitled to take part in the vote to choose the party's candidate for the 2016 mayoral race.
Lined up against Baroness Jowell - who was given a life peerage in last month's dissolution honours after quitting the Commons in May - and former shadow justice secretary Mr Khan were left-wing Hackney North MP Diane Abbott, Tottenham MP and lawyer David Lammy, former international development minister Gareth Thomas and transport campaigner Christian Wolmar.
Mr Lammy has called for an inquiry into the operation of the contest after claims that as many as one in five potential voters in the capital did not receive their ballot papers by the deadline of noon on Thursday.