Ed Miliband is pushing to be made chancellor if Andy Burnham becomes the next Labour Prime Minister, insiders have revealed.

The energy minister is said to maintain a close relationship with the Mayor of Greater Manchester, including giving him advice on economic matters.

But not all would be welcoming of the prospect of a soft-left Prime Minister and a soft-left Chancellor, with the combination of both potentially sending the markets into turmoil over fears of increased spending.

Mr Miliband has also previously come under scrutiny over the costs of his net-zero policies, including pushing to roll out thousands of electricity pylons across Britain to meet his 2030 targets.

He has however worked alongside Mr Burnham previously. During his tenure as Labour Party leader, Mr Miliband appointed the then-MP for Leigh as shadow health secretary, between 2011 and 2015.  

Now it has emerged Mr Miliband might be setting his sights beyond his energy remit should his long-standing colleague make it through the doors of Downing Street.

Mr Burnham is set to make his bid to become an MP this Thursday during the much-anticipated by-election in Makerfield. 

However, even if he is successful, he would still need to launch a formal leadership challenge against Sir Keir Starmer. 

In anticipation of that happening, Mr Miliband is said to be preparing his next move. 

One insider told The Telegraph: '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.'

Speculation over Mr Miliband's position comes as Sir Keir warned his MPs on Friday that a leadership challenge against him would plunge the country into 'chaos'.

The crisis-ridden premier vowed to fight any challenge against him by Mr Burnham because of his 'deep sense of duty'.

Sir Keir issued a warning to Mr Burnham that whoever replaces him will face the same crises and problems that have sunk his time in office.

He said: 'Whoever is prime minister is going to face the same prevailing winds as I am facing, none of that is going to change.

'For every answer that is being suggested, the question has to be, when you're in government, which is about trade-offs, what is it then that you wouldn't do?

'Because easy answers are by their nature easy. Decisions in government involve trade-offs.'

He begged Labour MPs to give him time to 'turn things around', as he insisted that he would not slink out of No. 10 without a fight.

Speaking to the BBC, he said: 'I'm not going to go away. I don't think we should plunge the country into the chaos of a leadership election.

'I don't think it should happen, but if it does, then I will fight.

'That's not about personal vanity. It's not about stubbornness. It's out of a very deep sense of duty.'

In a further swipe at Mr Burnham and former Health Secretary Wes Streeting, the Prime Minister said he has been 'concentrating on the job I was elected to do', while they 'have made their own case' to take his crown.

But Sir Keir's claim that a leadership challenge would plunge the country into chaos was ridiculed by his own MPs, one of whom hit back: 'As opposed to his chaos-free leadership?'

Two separate MPs branded the Prime Minister's position 'mental', with one adding: 'I don't know what's in the water at No. 10, but they need to get it checked ASAP.' 

And a fourth backbencher described Sir Keir's obstinacy as 'utterly insane', and demanded he 'recognise the game is up' for both him and Rachel Reeves 'for the sake of his family, for the sake of the party, and for the sake - most importantly - of our country'.

It is now understood that Sir Keir will not visit Makerfield to help Mr Burnham's campaign, despite previously voicing a desire 'to be part' of the effort.

Yesterday's interview with the BBC saw Sir Keir confronted with his own words used against Liz Truss when she was facing her own leadership crisis.

At the time, Sir Keir accused Ms Truss of being 'lost in denial about the turmoil she was causing' to the country.

On Saturday, Mr Burnham will make his last major public intervention of the campaign as he delivers a speech in Makerfield ahead of Thursday's polling day.

The constituency is also set to be flooded with up to 1,000 supporters of Restore Britain, the hard-right splinter party headed by Rupert Lowe MP that threatens to steal enough voters from Reform UK to allow Mr Burnham to sneak through the middle to victory.

A More in Common poll of the Makerfield by-election published on Friday evening put Labour on 45 per cent, Reform on 40 per cent and Restore on 8 per cent.