Andy Burnham has been warned against making Ed Miliband his Chancellor should he become prime minister – or risk his premiership being 'over before it's begun'.

Labour MPs, business leaders and the unions joined forces to express their alarm over reports that Mr Miliband would succeed Rachel Reeves in a Burnham government on the grounds that his high-tax, Net Zero obsessions are toxic to voters.

It comes as Sir Keir Starmer spends the weekend holed up in his Chequers country estate with his wife Victoria, pondering how to respond to Mr Burnham's emphatic win in Thursday's Makerfield by-election and his intention to challenge for PM.

Sir Keir has insisted he would fight any leadership challenge despite a growing number of Labour MPs and ministers urging him to set out a timetable for his resignation.

But one Labour source last night said: 'The only question now is the manner and timing of Starmer's departure. Everyone's focus is on who Andy puts in his Cabinet.'

Allies of former health secretary Wes Streeting, who has indicated his readiness to challenge Sir Keir, said that he was still deciding on whether to launch his own bid or cut a deal with Mr Burnham – and suggested that part of Mr Streeting's price for an agreement would be an assurance that Mr Miliband was not made Chancellor.

Mr Miliband, the Energy Secretary, has been repeatedly linked with the Treasury job as a reward for his support for Mr Burnham's plotting to enter the Commons.

Campaign aides say that Mr Miliband, who has privately urged Sir Keir to quit, calls the Burnham operation so often they can 'never get him off the f****** phone'.

His protege, Miatta Fahnbulleh, is working on Mr Burnham's policy prospectus and his former special adviser, Grace Pritchard, is now his spokesman.

Mr Streeting has distanced himself from Mr Miliband's 2030 target for decarbonising the entire electricity system – part of the total goal of achieving Net Zero emissions by 2050.

Critics say his policies – which include a moratorium on new drilling for oil and gas reserves in the North Sea – have pushed up energy prices during a cost-of-living crisis and rattled the markets, while his proposed ban on towel rails and underfloor heating amounted to 'Soviet-style interference'.

Senior Labour MP and former minister Graham Stringer said that Mr Miliband in the Treasury 'would be disastrous for Burnham's premiership'.

'The first thing Andy should do is reassure the financial markets – not spook them with a Liz Truss-style catastrophe by making Ed Miliband his Chancellor,' he said.

'And as for Burnham's pledge to re-industrialise the country, that would be destroyed straight away if he sent Miliband to the Treasury.

'As Energy Security Secretary, Ed's Net Zero zealotry has kept our energy prices high by putting on levies that are the highest in the world for industry and the fourth-highest in the world for domestic consumers.

'Miliband as Chancellor would be fatal for any re-industrialisation policy that Andy has.'

Mr Stringer added: 'In fact, I believe he should demote Miliband, not promote him. He should certainly lose his job as Energy Security Secretary as he has

been a disaster there. Burnham should keep Ed away from energy policy and industrial policy entirely if he wants to be a successful prime minister.

'Mr Burnham rightly talks about the need to address successive governments' neglect of the North. But Ed Miliband is toxic on the doorsteps in the North of England and has been since he was leader of the Labour Party.'

Another senior Labour MP said privately: 'Rachel Reeves may have to go but voters just don't like Miliband. He's toxic, especially in the North of England and in those parts of Scotland which have depended on North Sea oil and gas for jobs. Andy would be mad to make him Chancellor. If he does, Burnham's premiership would be over before it begins. He will be f***** from day one. The public hate him.'

They were joined by Sharon Graham, the leader of the Labour-supporting Unite union, who yesterday said that Mr Miliband was 'rushing to Net Zero with almost no thought for jobs, skills and national security'.

Ms Graham also urged Mr Burnham not to row back on Sir Keir Starmer's plans to water down electric car sales targets, called on him to reverse his opposition to a third runway at Heathrow airport and demanded he back a return to North Sea oil drilling.

Ken Costa, City grandee and former chairman of asset manager Lazard International, said: 'The essence of a good Chancellor is a pragmatic person who understands business. Miliband fails on both counts. He's an ideologue and has no business experience whatsoever.

'It would be a disaster for the business community if, in addition to a Left-wing prime minister in Burnham, you have an ideologically smitten Chancellor who will take his ideology into the financial markets.

'He will bring instability because everybody will be bracing for whatever bombshell he will drop next based on ideology rather than on the national interest. He should not be appointed [as Chancellor]. Appoint him anywhere else, but not there.'

Meanwhile, John Roberts, chief executive of Manchester-based retailer AO World, said: 'Ed Miliband would be a disaster. He commands no respect in the business community largely because the UK's cost of energy has been the biggest drag on growth.

'I never thought I'd say this, but I'd rather keep the consistency of Rachel Reeves.'

And Stephen Bence, chief executive of City law firm Vardags, said: 'I've spoken to several bosses who are leaving the UK because they are fed up with the negative change, anti-growth policies and business bashing.

'Appointing Ed Miliband [as Chancellor] would be doubling-down on an old-time socialist, anti-wealth agenda.

'What we need is a visionary who can turn the tide and get money back to Britain.

'As Andy Burnham has said, there are no second chances for Labour. One more wrong step and both they and the country will be irreparably screwed.'