Andy Burnham is expected to set out his economic agenda on Monday in his first major speech since announcing he would stand for the Labour leadership.
Reports suggests the former Greater Manchester mayor will use his speech to argue for a radical devolution of power and money away from Whitehall.
A long-standing proponent of devolution, Mr Burnham will set out plans to boost economic growth by giving regional mayors more control over social housing, welfare and post-16 education, according to The Times.
Such an agenda would be in line with the views he set out in his book, Head North, alongside his friend and fellow mayor Steve Rotheram.
In the book, Mr Burnham said the current system saw regional leaders going “on bended knee” to Westminster and called for a “more balanced approach, where councils and mayors were dealt some cards too”.
If Mr Burnham remains the only candidate for the Labour leadership, his speech will come exactly three weeks before he enters Downing Street.
Nominations for the leadership close on July 16, and if Mr Burnham is the only candidate he will be formally declared Labour leader at a special conference the following day.
But precedent states he will not become prime minister immediately, with the handover taking place on the next working day, July 20.
Meanwhile, Mr Burnham continues to mull his future cabinet.
Rachel Reeves appears to have conceded she will no longer be staying on as Chancellor, with several senior ministers including Home Secretary Shabana Mahmood and Energy Secretary Ed Miliband reportedly in the running to succeed her.
An unlikely alliance of some trade unionists and city traders have reportedly urged Mr Burnham against appointing Mr Miliband as chancellor, because they believe his net zero policies to be damaging.
But transport union the TSSA has thrown its weight behind Mr Miliband.
Questions also remain over whether Ms Mahmood will remain at the Home Office, with some Labour figures saying he should scrap her proposals to increase the length of time immigrants have to wait to apply for indefinite leave to remain in the UK.
Defence Secretary Dan Jarvis became the latest Cabinet minister to publicly back Mr Burnham as the likely next prime minister as he spoke to reporters on Saturday.
Mr Jarvis, who served as mayor of the Sheffield City Region while Mr Burnham was Greater Manchester mayor, told the Press Association: “I’ve worked very closely with Andy Burnham.
“He was an exceptional mayor of Greater Manchester and I think he will be an excellent prime minister, he understands the importance of national security and making sure that we’ve got the right amount of resource to invest in our armed forces.
“That is a process that is absolutely under way, but it is on the back of a commitment already to historic levels of defence funding.
“Yes, we want to do more, and the Dip will deliver that, and, yes, we want to go further, the other side of the Dip.
“That is well understood by Andy Burnham. It’s well understood by the current Prime Minister. It’s my job to deliver for defence and that’s what I’m working hard to do.”
Asked whether he would like to keep his job in a Burnham government, he said he was “very supportive” of the Makerfield MP but that decisions on cabinet posts would be a matter for the new leader.
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