Andy Burnham, the mayor of Greater Manchester who has long wanted to be prime minister, is used to being ridiculed at Westminster for his opportunism. Its latest manifestation, articulated in a series of attention-grabbing interviews on the eve of the party’s Liverpool conference, is his vainglorious attempt to undermine Sir Keir Starmer and position himself as the next Labour leader.

He and his supporters expected blowback, and it has been fierce.

Starmer and Rachel Reeves, the chancellor, regard the so-called king of the north with contempt and are scornful of his ambition to lead a Labour government that isn’t “in hoc to the bond markets”.

Their aides dismiss his alternative plan for Britain as a form of deluded retro-socialism. He is being compared to former Conservative prime minister Liz Truss, whose mini budget in 2022 precipitated an economic crisis. “Andy has cast himself as the challenger not a successor,” one senior adviser said. “Big mistake. He’s gone from being the king over the water to MacBeth.”

By seeking to destabilise an already fragile government, Burnham has angered many Labour MPs, who for all their frustration with the party leadership value loyalty. Timing is everything in politics, but has Burnham gone too early?

Burnham’s proposals include new wealth taxes and a higher top rate of income tax, widespread nationalisation of “public essentials”, devolving power to recapitalised local councils, looser fiscal rules, and a large-scale programme of council and social housebuilding. He wants to roll back the 1980s. “But to what?” one aide asked. “The crises of the 1970s?”

“Starmer has no political, cultural or economic plan,” countered Neal Lawson, one of Burnham’s key allies and co-founder of Mainstream, a new campaigning group. Lawson and Burham are appearing on a panel at Labour’s party conference in Liverpool to argue for electoral reform.

“Starmer’s hyper-factionalised approach has created the conditions for Labour to lose hundreds of seats and for Farage to be at over 30 per cent in some polls,” Lawson told me. “Why should we think that he can lead the transformation that the party seeks and the country needs? Andy has laid out an alternative plan for economic and social renewal and a new politics to build coalitions on the left. He has strong support.”

To mount more than a rhetorical challenge, Burnham would first need to return to the Commons via a by-election and secure the support of the party’s National Executive Committee and then at least 80 MPs. The Downing Street machine is determined to stop him through whatever means necessary, and the message from inside No 10 was blunt: “He’s fucked up.”

Starmer has long been suspicious of Burnham. Since standing down as an MP in 2017, Burnham has established a formidable, election-winning powerbase in the northwest. Unlike Starmer, he is a career politician; he knows how to build alliances and cultivate relationships. He relishes the game of politics.

In his early years at Westminster, by way of state school and an English degree at Cambridge, he seemed intimidated by Labour’s so-called golden generation of SPADs among whom he mixed – the Milibands, Balls, James Purnell, Yvette Cooper, Douglas Alexander. Today he is more at ease as a folksy, plain-speaking northern left populist.

What he shares with Starmer is relentless ambitious and the long-nurtured conviction that he should be prime minister. He first contested the Labour leadership in 2010. I chaired the opening hustings of that campaign at Church House, Westminster, where Burnham - a Blairite at the time and wearing what one wag described as his “dad’s suit” – took on the feuding Miliband brothers, Ed Balls and Diane Abbott, the candidate of the radical left. Burnham’s pitch that evening was “aspirational socialism” with Blairite characteristics, but it was clear to me that the Milibands and Balls did not consider him to be serious. Behind the scenes during the long summer contest, he was often condescended to and subtly mocked. I was repeatedly asked: what did he truly believe in?

My answer: he believed in Andy Burnham.

He stood again in 2015, this time in a new incarnation as the candidate of the soft left. He campaigned on how stultifying life was inside the “Westminster bubble”. He was crushed by Jeremy Corbyn. The Labour Party was entering another period of civil war, which paused only with the epic 2019 general election defeat and Starmer’s leadership victory. Now hostilities have resumed.

Since leaving Westminster Burnham has undertaken his most successful reinvention as a champion of municipal socialism or “Manchesterism” (he doesn’t mean 19^th century free trade liberalism). He speaks for many disaffected “soft left” MPs and party members disillusioned with Starmer’s faltering leadership, Reeves’s excessive caution, and a government adrift, lacking clear political and moral purpose or direction. His prominence serves as a warning sign of deeper unrest.

As Labour gathers for its annual conference in Liverpool, a mood of rebellion prevails among the parliamentary party. The left, the soft left, and even prominent Blairites, now describe Starmer as a “dead man walking”. They say he has failed to deliver the transformative change he promised, a failure reflected in both his own appalling approval ratings and the party’s dismal standing in the national polls.

But Starmer is fighting back. Emboldened by the Electoral Commission’s decision not to reopen the investigation into undeclared donations made when he was head of the Labour Together think tank, Morgan McSweeney, his chief of staff, scoffs at talk of the prime minister’s political mortality. After the turmoil of recent weeks, he and Starmer remain inseparable. They have made the changes they wanted to the No 10 operation and have the cabinet they want with the right people in the right positions.

And on Friday Starmer gave his most strategically coherent speech for a long while at the Global Progress Action summit in Westminster. He promised a “politics of patriotic renewal” which he contrasted with Nigel Farage’s “politics of predatory grievance”.

Renewal is now the defining word for Starmer. McSweeney speaks of “ripples of renewal” under Labour but conceded that it takes a long time for a ripple to become a wave of change. And Labour don’t have much time with the party so febrile.

A year ago, the Labour conference was also held in Liverpool, only a few months after the party’s landslide election victory. Yet the mood among delegates was despondent; this was not a happy or thriving government. Starmer was preparing to sack Sue Gray, his first pick as chief of staff, and much of the chatter then concerned her failings and how unprepared Labour was for power.

Now the conversation is all about Starmer - about what has gone wrong and whether his premiership can survive an abject performance at next spring’s local and devolved elections.

In a sense, Burnham’s self-aggrandising interventions have inadvertently aided Starmer. He now benefits from two clearly defined adversaries: one internal - Burnham - and one external - Farage. Meanwhile, Labour MPs have someone other than the prime minister and McSweeney to obsess about.

The self-styled king of the north has issued a direct challenge, personally and politically, to the London lawyer. He has gone hard and early and told the party who he is and what he represents: a mix of “business friendly socialism”, working class ambition, and a pointed indifference to the bond market. He claims this agenda can create a new political and economic settlement in Britain. Beyond that, as a pluralist and advocate of proportional representation, he believes he is well placed to lead a broad, multi-party “popular front” against Farage’s Reform UK.

Burnham’s Westminster opponents see him as deluded – he’s “MacBeth”, “Labour’s Liz Truss”, “an economic incompetent”. Yet many also welcome the clarity provided by his challenge. If Starmer isn’t galvanised now, he never will be.