Reform surge and Labour collapse signal a two-horse race ahead of 2026 Senedd election

PLAID CYMRU has hailed its sensational victory in the Caerphilly by-election as a “historic moment for Wales” — one that reshapes the nation’s political map and leaves both Labour and Reform UK nursing deep wounds.

The Welsh nationalist party, led by Rhun ap Iorwerth, seized the Senedd seat from Labour in what had long been one of its safest constituencies. Candidate Lindsay Whittle stormed to victory with 15,961 votes, fending off a fierce challenge from Reform UK’s Llŷr Powell, who polled 12,113.

Labour’s candidate Richard Tunnicliffe suffered a crushing defeat, taking only 3,713 votes — a collapse that has rocked the party’s century-long dominance in South Wales.

“Hope over division and progress over the tired status quo”

In a jubilant speech at the count, Plaid leader Rhun ap Iorwerth said the result proved that “the people of Caerphilly have chosen hope over division and progress over the tired status quo.”

He added: “We are now the real choice for Wales — the only party able to stop billionaire-backed Reform and offer a better future that works for everyone. Wales is ready for new leadership.”

Party officials described the win as a “seismic shift”, claiming it signals the emergence of a new two-party contest between Plaid Cymru and Reform UK in Wales.

Reform vows to fight on

Reform UK’s Llŷr Powell congratulated Plaid but insisted the party had achieved its goal of building a lasting grassroots presence.
“A big part of what we were trying to do here was to master our campaigning,” he said. “We’ve trained so many people up on our systems. We’re now a grassroots campaigning party.”

The result confirms Reform’s growing foothold in post-industrial South Wales, where concerns about immigration and living costs have driven sharp political realignments.

Labour’s red wall crumbles

For Labour, the by-election marks a devastating reversal. Once unassailable in Caerphilly, the party now faces what insiders privately call “the beginning of a meltdown.”

Labour’s Senedd member for Blaenau Gwent, Alun Davies, criticised his Westminster colleagues for “using the language of Reform” when discussing refugees and immigration.

Meanwhile, UK Cabinet Office minister Nick Thomas-Symonds defended the party’s stance, saying: “With regard to small boat crossings and securing our borders, that’s because people are telling us it’s a huge priority.”

Polling expert Sir John Curtice told broadcasters that Plaid is now “well-placed to lead the next Welsh government,” but cautioned that the result did not mean “Nigel Farage’s bubble is burst.”

“We are listening, we are learning”

Wales’s First Minister and Welsh Labour leader Eluned Morgan struck a contrite tone, admitting her party had failed to deliver change quickly enough.

“Welsh Labour has heard the frustration on doorsteps in Caerphilly that the need to feel change in people’s lives has not been quick enough,” she said. “We are listening, we are learning the lessons, and we will come back stronger.”

At the count, Deputy First Minister Huw Irranca-Davies compared the party’s situation to reports of Mark Twain’s death: “Rumours about death are greatly exaggerated,” he said. “We’ve bounced back before, and we will again — focusing on cost of living, jobs, and opportunities for young people.”

He also urged Plaid to work with Labour on passing its upcoming budget, warning that gridlock could hurt public services across Wales.

Immigration row dominates campaign

Although migration is not a devolved issue — and only around 3% of Caerphilly’s population were born outside the UK — Reform UK’s campaign made immigration its central message, accusing Labour and Plaid of supporting a “mass immigration agenda.”

Plaid’s clear pro-unity message, contrasting hope against hostility, was credited for cutting through. As one local voter put it: “Plaid talked about us, not about who to blame.”

Remembering Hefin David

In his victory speech, Lindsay Whittle paid tribute to Hefin David, the former Labour MS whose sudden death triggered the by-election.
“He will be a hard act to follow. I will never fill his shoes, but I promise I will walk the same path that he did,” Whittle said, drawing warm applause from both sides of the hall.

What the result means

Labour, which governs Wales with 29 of the 60 Senedd seats, now faces the risk of losing its working majority ahead of the 2026 election — and with it, control over key budgets. Political observers warn that Wales could be entering a new era of instability, where Plaid and Reform compete for disillusioned voters while Labour fights to redefine itself.

As one commentator noted: “Caerphilly has become a warning shot for Labour and a rallying cry for Plaid. What happens next could redefine Welsh politics for a generation.”

Photo caption:

Triumphant moment: Plaid Cymru’s Lindsay Whittle celebrates victory in Caerphilly as Labour’s century-long dominance crumbles (Pic: Matthew Horwood/Herald).