The upcoming Caerphilly by-election is being closely watched across Wales and the rest fo the UK, with many seeing it as a bellwether for the 2026 Senedd elections. Historically a Labour stronghold, the result could signal whether the party’s dominance in Welsh politics is waning, and whether new political forces such as Reform UK and Plaid Cymru are reshaping the electoral landscape.
A new poll of Caerphilly voters has sent shockwaves through Welsh politics, suggesting that Labour – long considered untouchable in the constituency – could be relegated to third place in next week’s by-election.
The survey, conducted by Survation on behalf of public affairs agency Camlas, sampled 501 local residents. While modest in size, it is the first poll to gauge opinion specifically in Caerphilly ahead of the October 23 vote.
The results are striking. Reform UK leads with 42% of the vote, followed closely by Plaid Cymru on 38%, while Labour languishes on just 12%. Historically, Caerphilly has been a Labour stronghold, represented by the party at both Westminster and the Senedd.
The figures mirror national trends, where Labour’s support across Wales appears to be in freefall. The party’s share in the most recent national poll fell to 14%, down from 40% in the 2021 Senedd election.
Rhodri ab Owen, managing director of Camlas Public Affairs, said: “All eyes have been on Caerphilly, as the by-election campaign is seen as a reflection of what is to come when Welsh voters head to the polls in 2026. The battle lines of Welsh politics have been redrawn. A dramatic generational shift is exhibited to be driving the future of Welsh politics as Reform and Plaid’s bases are concentrated in older and younger voter clusters respectively. Welsh Labour’s electoral dominance is potentially coming to an end with their dramatic 34 point drop in the polls and their support divided between Reform and Plaid Cymru.”
Key findings of the poll include:
- Reform UK enjoys strong support among older voters, claiming 49% of the 55+ demographic.
- Around 26% of Labour voters from 2021 now back Reform, alongside 18% of 2021 Plaid voters and a striking 70% of former Conservative supporters.
- Plaid Cymru is the dominant choice among younger voters, securing 50% of 18–34-year-olds. The party also attracts 31% of 2021 Labour voters and 19% of 2021 Conservatives who are wary of Reform.
- Labour’s traditional base has fragmented, with only a third (33%) of 2021 voters remaining loyal; 31% have shifted to Plaid and 26% to Reform. Remaining Labour support is concentrated among older core voters, reaching just 15% among those aged 55 and over.
- Conservative backing has largely collapsed, with approximately 70% of 2021 Conservative voters now leaning towards Reform.
Damian Lyons Lowe, chief executive of Survation, added: “Welsh politics is on the cusp of an unprecedented transformation. The Labour and Conservative parties previously took a combined 63% of Caerphilly’s Senedd vote in 2021, this polling indicates this may have plummeted to just 16% as both have seen an extreme fragmentation of their vote to both Reform and Plaid. While Labour’s one hundred year long unbeaten record in Caerphilly’s Senedd and Westminster elections is highly likely to be coming to an end, this type of result replicated nationally will also see the end of over 20 years of Labour Welsh Government dominance, with Reform or Plaid the likely party of power in 2026.”
A Plaid Cymru spokesperson said: “This poll confirms that the by-election is a two-horse race between Reform and Plaid Cymru. There is only one choice for those who want to defeat the ex-Tories and their politics of division – that choice is a vote for Plaid Cymru’s excellent candidate Lindsay Whittle. Lindsay has dedicated his whole life to serving the communities of Caerphilly. He is the only credible option for voters who want a principled, passionate and hard-working Senedd member and we urge everyone who wants to beat Reform to back him next Thursday.”
With polling day just days away, all eyes will remain on Caerphilly to see whether this traditional Labour heartland will deliver a historic shock – or if the party can stave off an unprecedented defeat.
