Andy Burnham is expected to seek the Labour leadership after his resounding victory in the Makerfield by-election.
If Burnham succeeds in gaining the keys to Number 10, here are some of the MPs and advisers who could be given key roles.
The former transport secretary was the first of Sir Keir's cabinet ministers to quit, after it emerged in November 2024 that she had a fraud conviction prior to entering parliament.
On the backbenches she emerged as a crucial power broker on Labour's "soft left", and was at the heart of the huge rebellion which scuppered the government's welfare cuts in 2025.
She has been a major figure in Burnham's Makerfield campaign, basing herself in the constituency, and is line for a big cabinet job.
Midgley has only been the MP for Knowsley, not far from Makerfield, since 2024 but she has been an influential force in the Labour movement for much longer than that.
She worked for Sir Keir's office in opposition following stints at the TUC, Unite and in former Labour leader Jeremy Corbyn's team.
She is seen as a plausible candidate for chief whip or even to be political secretary in Downing Street, not a job usually held by an elected politician.
Fahnbulleh resigned as a junior minister for communities in the aftermath of the May elections, but unlike most of those who quit the government she is from Labour's soft left, not its right.
Since then she has been working on policy ideas for a potential Burnham government. She was previously a civil servant and ran the New Economics Foundation think tank.
The man who gave up his seat for Burnham - and who was praised for his "selflessness" by the new Makerfield MP, in a speech to supporters on Friday morning.
Simons is said to have been helping Team Burnham on policy, though he has a different ideological background to Fahnbulleh.
He has been on a rapid political rollercoaster: he worked for and then fell out with Jeremy Corbyn; ran a pro-Starmer think tank; became an MP and quickly a minister, from which he had to resign over accusations about his conduct at the think tank.
He is seen as a likely candidate for a role in a Burnham Downing Street.
Currently Burnham's deputy mayor for policing and crime, Green has been canvassing MPs about their opinions on what a Burnham government should do and is seen as a possible candidate for a role in Downing Street.
Before taking up her current role in 2023 she was an MP for 12 years, including a stint in Sir Keir's shadow cabinet.
Burnham's closest adviser, Lee ran his first Labour leadership campaign in 2010, advised him when he was shadow health secretary and has been running his mayoral office since 2017. A dead cert for a role in a Burnham Downing Street.
As the independently-elected deputy leader, Lucy Powell has her own big role to play regardless of who the Labour leader is.
But as it stands she is not in the cabinet so only has influence over party matters and not the government.
This is likely to change should Burnham become prime minister. The pair have worked closely together for years given she is a Manchester MP.
When Miliband won the Labour leadership in 2010, Burnham came fourth. In that contest Burnham positioned himself to Miliband's right.
Years later, the two have become aligned in their belief in a more interventionist state.
Many around Sir Keir are deeply suspicious to say the least of Miliband's behaviour as energy secretary over recent months, believing he has been agitating for Burnham behind the scenes.
He is thought to covet the role of chancellor, having spent many years advising Gordon Brown in the Treasury under New Labour.
Only four MPs are left who voted for Burnham to become leader the first time he tried, in 2010. One of them is Alexander, now the transport secretary.
She also backed him in 2015, a race he began as frontrunner, and is likely to be in line for a big job should he win.
A veteran figure on Labour's progressive left as the founder of the pressure group Compass, Lawson has also been a leading figure in the fairly new organisation Mainstream, which has generally been seen as Burnham-aligned.
But his ideas on electoral reform and alliances between progressive parties sit uneasily with others in Burnham's orbit - it will be fascinating to see if Lawson is given a role or not.
Burnham consulted high-level advisers, especially on economics, in the days before his by-election win in Makerfield.
In a sign he is preparing programmes for national policy, and to communicate stability to the markets should he become prime minister, Burnham has been taking advice from Lord O'Neill, a former Treasury minister and economist.
He has also been advised by Hughes, the former chairman of the Office of Budget Responsibility, who resigned after an IT leak of Budget numbers.
