Andy Burnham is poised to move into Number 10 Downing Street on Monday, having secured the necessary nominations from Labour MPs and trade unions. While the leadership contest is settled, a significant under-the-radar battle is underway for the crucial position of chancellor of the exchequer, who will serve as Burnham's close advisor and neighbour.

The choice of chancellor will send a powerful signal about Burnham's economic intentions to both political allies and the vital bond markets. The official stance from Burnham's team is that no decision has been finalized, with cabinet appointments expected to be announced upon his move to Downing Street.

Discussions have been ongoing within a small circle, including incoming Number 10 chief of staff James Purnell, Louise Haigh, and Josh Simons, who stepped aside to allow Burnham's by-election victory. The initial assumption following Burnham's win was that Energy Secretary Ed Miliband would be appointed to the Treasury.

However, various influences, from unions representing oil and gas workers wary of Miliband's approach to Lord Walker, Iceland supermarket boss and the former leader's unpaid 'cost of living' tsar, have attempted to shape the decision. Lord Walker reportedly argues that an ideologically driven chancellor could unsettle the bond markets.

Recent indications from MPs close to Burnham suggest that Miliband's prospects for the chancellorship may have diminished, though they emphasize they are observing the mood rather than making the final call. Supporters of Miliband maintain his appointment remains highly possible and desirable, highlighting his economic background, experience as a Treasury advisor under Gordon Brown, and his tenure chairing the Council of Economic Advisers.

Those close to Miliband point to his ministerial experience in previous Labour governments and his ability to implement policy within the Treasury. They also stress his alignment with Burnham's goal of spreading economic growth across the country, with supporters emphasizing his fiscal prudence and adherence to debt and borrowing rules.

Some within the parliamentary party anticipate Miliband's move to Number 11. If he is not appointed, sections of the party's soft left may perceive it as Burnham hesitating to enact significant change.

Other influential figures have been advising Burnham, including Lord Jim O’Neill, former chief economist at Goldman Sachs and commercial secretary to the Treasury, and Andy Haldane, former chief economist at the Bank of England, who were driving forces behind initiatives like the Northern Powerhouse and the Cities Growth Commission.