Welsh Labour is the democratic world’s most successful election-winning machine, coming first in Wales in every general election since 1922 and every devolved election since 1999. Come next month’s Senedd election, however, this history-making run is expected to end.

Labour’s collapse has left a vacuum, and former Labour voters are going to opposite ends of the political spectrum. Plaid Cymru and Nigel Farage’s Reform UK are neck and neck in the latest poll, although coalition maths make it highly unlikely Reform would be able to form a government.

The possibility of Labour losing power after 27 years and the pro-independence Plaid entering government as a senior partner for the first time means “this election is huge”, said Laura McAllister, a professor of public policy at Cardiff University.

Welsh Labour – and Wales itself – is at a crossroads, she added. “I’m not sure people have computed yet how existential both those things simultaneously are going to be.”

Losing Wales after a century would be yet another blow to the beleaguered prime minister, Keir Starmer, and the wider Labour party, and would be likely to amplify already loud calls for him to resign. Separatists in office in all three devolved nations for the first time – Plaid Cymru in the Senedd, the Scottish National party (SNP) in Holyrood and Sinn Féin in Stormont – would mean that whoever occupies No 10 Downing Street in the near future will have a constitutional fight on their hands.

Welsh Labour, met with lacklustre receptions on the doorstep and with a very different future for Wales coming into view, is bracing for what one senior source described as a “critical debate about what the party stands for” after the election.

“There will be those who try to defend 27 years in power, and attribute blame for a loss to the UK government or other factors,” they said. “But you have to be humble in losing. You have to understand why you lost the public’s trust and support and what needs to be done to stay relevant.”

Welsh Labour’s record in office is mixed. The Welsh embarked on the devolution process more cautiously than Scotland and Northern Ireland, and initially very limited powers hampered Cardiff Bay administrations from the outset.

Supporters insist the party held the line against 14 years of Conservative government in Westminster, protecting public services from the impact of austerity, Brexit and the Covid pandemic.

But after 27 years of devolution, Wales has fallen behind the other UK nations in several key metrics. About 20% of Welsh NHS patients have to wait more than a year for hospital treatment, compared with about 4% in England.

Welsh children’s reading, maths and science skills fell to the lowest recorded OECD assessment levels of the four nations in 2024, and the proportion of people in Wales considered to be in very deep poverty rose from 33% in the 1990s to 47% in 2023, according to the Joseph Rowntree Foundation.

Labour is faced with the tricky task of offering both stability and change: one campaign slogan is “a new chapter”. Launching the party’s Senedd manifesto, the first minister, Eluned Morgan, said: “I think we’ve got to be honest about where people are. You’ve all heard it on the doorstep … People are right to hope for more, and I share your impatience. Your longing for change is my own.”

The scandal-plagued premiership of Vaughan Gething – who was first minister for just four months in 2024 – was highly damaging, riving the party internally and repulsing voters. Starmer’s election was expected to strengthen Welsh Labour as a “partnership in power” in Cardiff and London, but his unpopularity appears to have weakened it instead.

Starmer’s government has saved jobs at Tata Steel in Port Talbot, decided that the country’s first small modular reactor (SMR) nuclear power station will be built in Ynys Môn (Anglesey), and taken steps to address Wales’s unfairly underfunded rail network. Yet Westminster intervention has not staunched the Welsh branch of the party’s precipitous decline; the prime minister’s name is not mentioned at all in the party’s manifesto.

“Starmer’s government has done more for Wales already than the Tories did in 14 years. But there’s so much general anger at everything on the doorstep … Public expectation is harder than anything opposition can throw at you,” the Welsh Labour source said.

Morgan, elected as leader unopposed as the party put on a united front after the Gething fiasco, was arguably always going to have to fight an uphill battle.

The Cardiff-born first minister is personable and approachable; she DJs at conference parties and is good at making people laugh. She has also spent her political career campaigning for devolution and greater powers for Wales, but her party’s failure to deliver quickly enough for a jaded electorate means she may end up losing her seat.

“Eluned is relatively new and hasn’t had a chance to prove herself yet. She deserves that chance,” said another senior Labour source.

The polls make grim reading for Labour loyalists. The latest two from YouGov suggest the party will finish third with 13% of the vote, which translates into just 12 seats in a parliament that is growing from 60 to 96 members under a new electoral system.

McAllister said: “There’s an argument that the Welsh public going from Labour to Plaid and Conservative to Reform is more of a realignment than a big switch. So there’s some hope for Labour there: how sticky is that switch? If Plaid don’t do well, don’t deliver, voters could swing back.”

The new system has created 16 super-constituencies, each of which will elect six members; by the time the sixth seat on the list is decided, just a handful of votes could make the difference, making results very hard to predict.

At least one of Welsh Labour’s anticipated election woes is directly of the party’s making. In 2022, the special purpose committee on Senedd reform laid out several more proportional voting methods as options for 2026.

People involved in the negotiations said that while some Labour members, along with Plaid Cymru, were in favour of a single transferable vote (STV) system, most of the party argued for the closed-list D’Hondt method, which lets voters choose parties as a whole, rather than individual candidates.

Control over names on the lists suited hierarchical Welsh Labour; that D’Hondt tends to favour bigger parties also appealed.

Prof Richard Wyn Jones, the director of Cardiff University’s Wales Governance Centre, said: “There’s a huge irony that it was Labour’s choice to have this system. If they’d gone for STV or the other options on offer, they would have done better.

“It appears no one in the Welsh parliamentary Labour party ever imagined they could be a small party.”

Plaid Cymru may be the only party able to form a government after the election, because while Reform could win the most seats, the Welsh nationalists and Labour have ruled out going into coalition with Farage’s outfit. But the latest YouGov poll this week put Plaid Cymru on 36 seats, down seven, making a scenario in which Plaid need to turn to Labour as a coalition partner more likely.

Plaid Cymru and Labour have entered formal coalition and cooperation agreements before, but McAllister said there was “no value” for Labour in becoming a junior partner in the next Welsh government.

“What would they gain? I also think the nationalist rhetoric, and propping up a nationalist government, would be too hard to bear, being seen as Plaid’s helpers rather than the other way around.”

For many in the party, the glory days of the late 1990s, when New Labour opened the door to devolution, work began on the Welsh-slate Senedd building, and the first minister Rhodri Morgan overcame the new national assembly’s teething problems to lead Wales into a new millennium, feel like a long time ago.

Rhodri Morgan’s decision to rebrand Labour in Wales as Welsh Labour was successful on several counts. It cemented the idea that the party was distinct and more progressive than UK Labour, stopped soft-nationalist voters from embracing Plaid Cymru, and ingrained devolution as the new normal.

After almost 30 years, however, it seems Rhodri Morgan’s “clear red water” – reinvented by Eluned Morgan as the “red Welsh way” – appeals less to voters who now take devolution for granted, and increasingly identify as more Welsh than British.

“I don’t think it has to be binary, are you Welsh or are you British,” said a third senior Labour source. “Labour delivered devolution and Labour got Wales the powers it has today. I know there’s a big chunk of people toying with the idea of voting for Plaid Cymru but there are also still people out there that know Labour is loyal to Wales.”