By Christian Edwards, CNN

(CNN) — UK prime minister Keir Starmer announced his resignation on Monday.

In July 2024, the Labour Party secured a landslide general election victory after 14 years in the political wilderness. But it took the British government not quite 24 months to tear itself apart.

The party had promised to end the chaotic churn at the top of government seen under the Conservatives, but on Monday Keir Starmer announced his plan to step down as leader just two years into his term. His successor, once chosen, will become Britain’s seventh prime minister in a decade.

Less than two years ago, Starmer led Labour to its biggest majority in Parliament this century, consigning the Conservatives to their worst-ever defeat. But the British public soured on Starmer almost as soon as it elected him. He survived months of scrapes, but in the end the pressure for him to quit became too great to withstand. Starmer leaves office as the least popular prime minister on record.

There is, however, a sense of bewilderment in Britain as to how things went wrong so quickly. Unlike his predecessors, Starmer did not join a despised foreign war, or botch a pandemic response, or crash the economy. His missteps were more mundane: an attempt to make wealthier pensioners pay more to heat their homes; a plan to cut some benefits to disabled people; accepting freebies; and, in recent months, a scandal over his appointment of Jeffrey Epstein-linked politician Peter Mandelson to the role of UK ambassador to Washington.

Policy missteps alone cannot explain Starmer’s fall. There are two other glaring factors. The first is his inheritance. When Starmer took office, Britain was worn out by the Conservative program of austerity. That decade of cost-cutting aimed to reduce Britain’s debt and aid its recovery following the 2008 financial crisis but failed on both counts: Debt has ballooned and economic growth has been anemic since.

Tired of stagnation, Britons were impatient for better times and hoped Labour could provide them. When a Labour government last took office in 1997, it rode in on a wave of optimism, soundtracked by D:Ream’s “Things Can Only Get Better.” Starmer struck a different tone. In his first major speech as prime minister, he told people it would take years to fix Britain’s foundations and that “things will get worse before they get better.” After the heady have-your-cake-and-eat-it premiership of Boris Johnson, some thought Britain was ready for hard truths and would forgive Starmer his dire inheritance. They were mistaken.

The second reason for Starmer’s fall is more personal. He failed to set out an easily expressed political philosophy. Lacking the narrative glue that holds a governing project together, many of Labour’s decisions seemed arbitrary. Starmer floundered in part because “Starmerism” never existed.

Instead of a big-picture political idea, Starmer was meant to stand for due process. He entered politics in 2015 after a distinguished career in human rights law, which saw him become the national director of public prosecutions. He served in the shadow cabinet of Labour’s hard-left leader Jeremy Corbyn. After a crushing election defeat in 2019, Starmer was chosen as Corbyn’s successor – seen as a safer pair of hands after Labour’s years of radicalism.

In opposition, Starmer’s skills in cross-examination helped him to hound three Conservative prime ministers at the dispatch box. Seizing on public anger over “Partygate” – where Conservative lawmakers flouted their own laws on Covid-19 lockdowns – Starmer increasingly appeared a prime minister-in-waiting.

But the closer Labour got to power, the more cautious it became. Even when polls predicted a landslide win before July 2024, Labour pursued a “Ming Vase” strategy, moving as though one slip could shatter their commanding poll lead. Wanting to appear as non-threatening as possible, they tempered their ambitions for government and refused to dream big.

That caution was costly. The Conservatives, anticipating a heavy defeat, announced sweeping tax cuts before the election, expecting that Labour would have to raise them once in office, given the parlous state of Britain’s public finances. Instead, wanting to avoid renewing Labour’s image as “the party of tax rises,” Starmer ruled out raising the three main sources of taxation, including income tax.

Labour spurned the chance to tell a positive story about the need to hike taxes to mend Britain’s public services, gutted by years of Conservative austerity. That decision, taken in opposition, became a straitjacket for Labour in government. The party had to raise taxes from smaller, more vulnerable sources.

Shortly after taking office, Labour said it would end a universal subsidy to help older people pay their heating bills in winter, alongside cutting some benefits to disabled people. After a backlash, it backtracked on both plans. To its left-wing voter base, Labour seemed callous. To financial markets, it seemed unwilling to take tough decisions.

If the government’s economic policy seemed rudderless, so did its stance on immigration. Starmer announced early that Reform UK was Labour’s main electoral threat, elevating the upstart hard-right party – which won just five seats in Parliament in the 2024 election – to the de facto opposition. Labour then spent months trying to stem Reform’s growth by appealing to right-wing voters with tougher rhetoric and policies on immigration.

The strategy backfired: Labour alienated its progressive voter base, many of whom flocked to the Liberal Democrats or Green Party, while Reform surged in the polls. When Starmer then tried to soften his stance on immigration, it seemed inauthentic.

His government was also rattled by scandals. Starmer was criticized after it emerged that he had accepted more freebies than any other member of the previous parliament, including tickets to Taylor Swift concerts and Arsenal matches. The scandal might not have been so damaging had Starmer not cast himself as a man of process who, after years of perceived Conservative cronyism, would keep everything above board.

The most damaging scandal, however, came over Starmer’s decision to appoint Mandelson to the plum ambassadorial role in Washington despite the veteran Labour politician’s well-known ties to the pedophile Epstein. Although Starmer fired Mandelson in September, once those ties became clearer, he was hounded for months over what he knew and when about whether security officials judged Mandelson fit to serve as one of Britain’s top diplomats.

In the end, the leader who was meant to stand for due process was brought down by his government’s failure to observe just that. A resounding defeat for the party in May’s local elections only served to illustrate the depths to which his government’s popularity had plunged, prompting a slow-motion leadership contest to replace him.

When leadership hopeful Andy Burnham won a resounding victory over his Reform rival in a by-election last week, giving him a seat in parliament and with it the chance to launch a challenge, it became clear that Starmer’s days in Downing Street were numbered. Other senior Labour figures could also enter the race, with a new leader expected to be in place before the new parliamentary session begins in September.

Starmer’s faults might have been forgiven if he were more charismatic, or if he had a bolder plan for government. But he came to resemble a manager, believing that Britain’s problems could be solved by mere tinkering, rather than radical change.

In lieu of a clear vision, Starmer instead promised hard, grudging work to “root out 14 years of rot.” He would mend Britain’s ties with Europe, strained after the painful Brexit negotiations, and improve relations with China, which had entered an “ice age” under the Conservatives. He would bring NHS waiting lists down, build new homes and cut people’s bills. It would not happen overnight, he cautioned. But the country wanted swifter results.

As he announced his resignation in front of 10 Downing Street, Starmer insisted he was leaving his party, and Britain, in a better place than when he took office.

But he acknowledged there were questions over whether he was best placed to lead Labour into the next general election.

“I have heard the answer of my parliamentary party to that question, and I accept that answer with good grace,” he said. “Every decision I’ve taken has been about putting the country I love first. That is why I will resign as leader of the Labour Party.”

The impression Starmer leaves is of a man who might have been a serviceable 20th century prime minister, when more was kept behind closed doors and government happened quietly. But in his own time – less patient, more visual – he floundered.