Ed Miliband has been tipped to become the Chancellor of the Exchequer if Andy Burnham is victorious in his bid to replace Sir Keir Starmer.
The pair have been colleagues for over a decade, even before the Energy Secretary became Labour's leader and continue to speak on a regular basis, party insiders said.
The Doncaster North MP has already chipped in with some economic guidance, suggesting obeying Whitehall's fiscal rules to cool the nerves of the bond markets.
"Ed is clearly working on the basis of that is what he wants (to be Chancellor) and that’s what he is assuming he will get," a close ally of Mr Burnham told The Telegraph.
Facing the prospect of packing her bags and leaving No11, allies of Rachel Reeves have been rallying behind the Chancellor, insisting she must not be replaced if the Prime Minister is forced out.
They warned that switching out the Leeds West and Pudsey MP could risk "spooking" the markets.
"If there are future debates around fiscal flexibility, defense spending or how we unlock growth more aggressively, there is only one person currently capable of doing that without spooking the markets or risking another self-inflicted crisis," one minister told Politico.
"The country cannot afford a repeat of the (Liz) Truss experiment."
The Greater Manchester Mayor is understood to be prepping his frontbench
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The Greater Manchester Mayor is understood to be readying his top team should the opportunity to oust the Prime Minister arise upon his possible return to Westminster.
The Makerfield by-election is creeping ever closer and will take place next Thursday.
Latest polling projects that Mr Burnham could scoop up 45 per cent of the vote, while Reform UK comes in second place on 40 per cent.
Fears have been raised that Restore Britain could be fracturing the right-wing vote, with Rupert Lowe's party due to take home eight per cent.
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The pair go way back
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During Mr Miliband's leadership, Mr Burnham served as Shadow Education Secretary and, later, became Shadow Health Secretary.
But, with a potential Miliband chancellorship looming over Whitehall, rumours have flooded SW1 on what such an appointment would look like in practice.
Some Government sources have suggested that a former leader would soothe the panicked markets, arguing that Mr Miliband has been an advocate for welfare reform.
One source told The Spectator: "They think Ed can be Chancellor. He wanted the crown jewel of the 2010 manifesto to be the "Better Off in Work" guarantee – that work would always not only pay more than welfare, but pay much more than welfare.
"That tells you about where Ed comes from."
The Energy Secretary is already challenging Sir Keir over potential cuts to the Department for Energy Security and Net Zero to fund defence.
The cuts would fund the long-awaited Defence Investment Plan (DIP), which caused a stonking headache for the Prime Minister yesterday when John Healey, Al Carns and PPS Pamela Nash resigned.
Sir Keir could be eyeing up axing some of Mr Miliband's treasured green projects in Whitehall to divert spending into protecting Britain instead.