The Conservatives and Reform UK, however, are preparing to attack his policies, questioning how they will be funded and whether there will be new tax rises.
Kemi Badenoch reshuffled her shadow cabinet team on Monday in preparation for this moment. To sharpen her party’s attacks on Labour over its handling of tax and the economy she promoted Andrew Griffith to be her new shadow chancellor.
The Conservatives are making much of his past jobs in business. Before entering politics he was chief financial officer and chief operating officer at Sky, and chair of Just Eat.
He is promising a Conservative government that would deliver “lower, simpler taxes, get Britain drilling again to bring down energy costs, slash the red tape holding Britain back, and scrap the job-killing measures in Labour’s (Un)Employment Rights Act”.
Labour and the Liberal Democrats have seized on the fact Griffith was a Treasury minister in Liz Truss’s government and publicly defended her “mini-budget”.
Bridget Phillipson, the Labour Party chair, said the “Tories’ top team is crammed full of the same vandals who hammered family finances and left our public services crumbling”.
Liberal Democrat Treasury spokesperson Daisy Cooper said Griffith’s appointment showed the Conservatives were “happy to forfeit any claim to economic credibility”.
Burnham will face criticism from the Greens too. Their leader, Zack Polanski, says that Burnham’s ideas for greater public control over vital services is “just tinkering”.
Polanski says “if he really wants to bring back hope, he needs to tax the wealthy, take water and energy back under public ownership, bring in rent controls, and say no to new North Sea drilling”.
The Liberal Democrats are already attacking Burnham’s plans to deal with the prisons crisis.
Their justice spokesperson, Jess Brown-Fuller, said Labour’s promise to build new cells was not backed by any new money and proved “just how unserious this Government remains about fixing our justice system”.
Other major challenges facing Burnham include defence. How will he fund the plans he has inherited from Sir Keir? And, beyond that, how fast will he increase spending to meet Nato commitments?
There are imminent decisions to be made about whether to approve new drilling for oil and gas in the North Sea. There are looming choices about whether to do more to help as energy bills rise this winter, whether to increase taxes at the Budget. And longer-term issues about reforms to welfare, social care and ties with the EU.
All of which means that the moment when Burnham rises to address MPs on Tuesday may well be the point when his honeymoon period as prime minister ends and the hard work begins.