MANCHESTER, England—On a rainy afternoon just over a month ago, Andy Burnham drove around the low-key northern town of Ashton-in-Makerfield in an old red Ford Fiesta, kick-starting one of the more outlandish political takeovers in modern British history.
Accompanied only by Kevin Lee, his leather-jacket-wearing adviser, the then mayor of Greater Manchester knocked on doors with an unusual request: Vote for him in a local election so he could enter Parliament and oust the leader of his own party, Prime Minister Keir Starmer.
Now, Starmer is on his way out, and Burnham is set in coming weeks to become Labour leader and the U.K.’s 59th prime minister. He will likely be ushered into Downing Street without a formal leadership contest or detailed plan for power—on the strength of winning 24,927 votes in Makerfield.
In a matter of weeks, he will have gone from cheerleading a city to being in charge of the world’s fifth biggest economy and a nuclear-armed power, and from overseeing a budget of £3 billion to one of £1.4 trillion.
“This definitely feels surreal now,” Burnham said as he walked into his parliamentary office in Westminster recently.
Even if British politics has become increasingly unstable, the abrupt rise of Burnham, 56, reads like a low-rent mashup of “House of Cards” and “Monty Python,” leaving even scandal-hardened politicos bemused.
The ascension of Burnham owes less to secret machinations in smoke-filled backrooms than it does sheer circumstance. He happened to have the right political brand at the right time, and something no other major Labour politician could boast: a net-positive approval rating.
The rise has been so sudden that Burnham and aides last month rushed to hold a series of meetings in his backyard to start hashing out governing policies.
“The idea that he descends on Westminster like he is a conquering hero, it doesn’t have a logic,” said Philip Cowley, a politics professor at Queen Mary University of London. “But sometimes in life logic doesn’t matter.”
In the U.K. it isn’t unheard of for prime ministers to be replaced mid-term. Unlike in the U.S., voters in Britain voters endorse political parties, not prime ministers, during elections.
But the bloodless coup two years into Starmer’s term, along with the swift rise of and lack of scrutiny over his replacement, is raising eyebrows. Nominations are due to officially open next week, but Burnham is expected to be the only candidate to throw his hat in the ring. If no one else does, then he becomes prime minister by default as early as July 20.
At the heart of Burnham’s political takeover is a much slower-moving makeover—from a onetime political insider to outsider who is now returning to government, a good look when trying to appeal to voters who mistrust mainstream politicians.
The soccer-mad northerner spent his early years in politics toiling under prime ministers Tony Blair and Gordon Brown. He failed twice to become party leader, in 2010 and 2015, partly because lawmakers saw him as an establishment figure.
“He was seen as tainted,” said Peter Soulsby, the mayor of Leicester, and a former lawmaker who had previously backed Burnham to lead Labour.
So in 2017, he left Westminster to head to Manchester and spent nine years as a metro mayor, far from the increasingly dysfunctional national politics. There, he inherited a feel-good story: Britain’s second-largest city was enjoying a turnaround after years of deindustrialization thanks to a more active local government and rush of private investment.
While Burnham was away, British politics endured its toughest stretch since the late 1970s, with Brexit, the pandemic, the war in Ukraine, an inflation-hit economy and a string of scandals turning voters against Westminster.
Now, Burnham is marketing himself as the one who can reshape British politics and re-engineer the British state, partly by busting up the concentration of power in London.
This week, Burnham, dressed in a T-shirt and blazer combo that has become the sartorial expression of his outsider status, walked into a Manchester museum to give his first official speech laying out his vision for Britain. “Are you ready for this?!” he said to a small band of supporters.
During a 20-minute speech, he pledged to rewire the British state to give more decision-making power to the regions, build more social housing than at any time since World War II, re-industrialize the country and try to inject a bit of hope back into politics. He also pledged to move part of the Downing Street operation to Manchester. There were no details over how he intended to pay for his policies. He then left via a side door without taking questions.
Commentators are already drawing parallels between Burnham and another mayor turned prime minister: Boris Johnson. The Conservatives parachuted Johnson, a chaotic but charismatic former mayor of London, into the prime minister’s office in 2019 on the premise he could win a new general election and deliver Brexit. Johnson did both, but then was ousted in 2022 after a long line of scandals.
Starmer won the next election in 2024 on the premise he was nothing like Johnson. He was a former prosecutor who entered Parliament late in life, the unspoken pitch being that he would bring some dull normality back to British politics. Starmer’s asset, however, soon turned into a liability as a dry style failed to energize voters or his lawmakers, who soured on him following a series of ham-handed policy changes, including an ill-communicated attempt to curb welfare spending.
As Britain’s economy continued to stagnate, Labour’s voter base fractured and anti-immigration party Reform UK leapt ahead in the polls. Many of the new Labour lawmakers who had entered Parliament in 2024 on thin majorities began to fear that Reform would take their jobs in the next election.
As Starmer’s government began to struggle, and his approval ratings fell, Burnham began throwing peanuts from the gallery.
Last September he traveled to Labour’s big annual jamboree in nearby Liverpool and openly said lawmakers were privately urging him to challenge Starmer and promote a more left-wing platform. It proved the start of a sustained pressure campaign.
A month later, a group of center-left lawmakers created the Tribune Group to push the party in a more progressive direction to tackle Reform, spearheaded by Louise Haigh, a former Labour cabinet minister. Nearly a year before, Haigh had been fired by Starmer over a decade-old fraud conviction.
Soon, the caucus had the backing of around a quarter of the Labour Party.
The Tribune Group set out policies that chimed with Burnham’s own economic vision—that utilities needed to be brought back under state control and that the state needed to borrow more to invest in infrastructure. They also wanted more tax on capital.
According to people familiar with the group, the initial goal wasn’t to oust Starmer, but rather to pressure him to move left. A turning point came in February, when the Labour Party came third in a special district election in northern England, behind Reform and the Greens. Some cabinet members began discussing how to move Starmer on and looking at polling for potential replacements.
The problem was that polling showed every Labour cabinet minister was also disliked by the electorate. Only one person had positive approval ratings: Burnham. The twist: As mayor, he wasn’t eligible to stand as leader. He needed to be elected to Parliament first.
Starmer initially blocked Burnham from standing as a lawmaker. Then, in May, the Labour Party logged its worst local election results in modern history and the prime minister’s political capital evaporated as panic set in.
A Labour lawmaker in the northern district of Makerfield agreed to make way for Burnham to run. Starmer no longer had enough power to stop him. The Labour Party poured resources into the district, and Burnham easily defeated Reform.
Starmer read the writing on the wall and quit.
A few days later, Burnham, dressed in a T-shirt, boarded a train from Manchester to London. By the time he stepped off the train in the capital, he was wearing a suit.
Write to Max Colchester at Max.Colchester@wsj.com