Three economic heavyweights have been brought in to advise Andy Burnham as he attempts to reassure the markets before his return to parliament and possible challenge to Keir Starmer.

Burnham is understood to be getting advice from Andy Haldane, a former Bank of England chief economist, as well as Richard Hughes, a former chair of the Office for Budget Responsibility and Jim O’Neill, a crossbench peer and former Treasury minister who worked on George Osborne’s “Northern Powerhouse”.

Burnham’s decision to bolster his team of economic advisers, first reported by Bloomberg and the Financial Times, suggests he is keen to signal his fiscal credibility. The extent of their involvement in drafting economic plans is not yet clear.

The Greater Manchester mayor won the crucial Makerfield byelection by a huge majority on Friday, paving the way for a challenge to Starmer’s leadership.

No 10 and the Treasury will be closely watching the bond markets on Friday morning for any sign that gilt investors are worried about higher borrowing or the economic instability brought about by a possible change in leader and chancellor.

Burnham is expected to attempt to oust the prime minister within weeks, first by trying to persuade him to stand down. If Starmer declines to set a date for his departure then Burnham is likely to launch or join a contest, with his team confident of more than the necessary 81 MPs backing him.

But allies of Starmer have warned the country and economy could be destabilised by a leadership contest.

Aside from the effect of a leadership battle, some within Labour believe Burnham still has to make a case he can convince the markets to stay calm after he previously suggested the country should be less in hock to the reaction of bond traders.

He has since smoothed over his remarks, saying they were misinterpreted. He told the FT: “What I’ve said is we had a way of running the economy over a long period of time where we just gave up control of the fundamental drivers of the economy.”

He has also said he has no plans to change the fiscal rules that the chancellor, Rachel Reeves, committed to before the last election.

Ahead of his likely challenge to Starmer, there has also been huge speculation over who he could appoint as a chancellor. Names mentioned include the energy secretary Ed Miliband, John Healey – who resigned as defence secretary last week – or even his leadership rival Wes Streeting.

Haldane, who is the chief executive of the Royal Society of Arts, earlier this year urged the Bank of England against interest rate rises and set out how war bonds to raise money for defence could work.

Hughes, who resigned last year after the OBR accidentally published Reeves’s budget too early, is now a senior economic adviser at the London-based fund manager Taula Capital.

O’Neill recently wrote a blueprint to get the economy going, endorsing a bond- and equity-market rally, a construction boom, higher business and consumer confidence, and the political dividends that come with broad-based gains to voters’ standard of living.

Haldane, O’Neill and Hughes did not immediately respond to requests for comment.