The Caerphilly by-election: a glimpse into Labour’s troubles in Wales
9 October 2025 | Rob Fellows
By Rob Fellows, COO
The upcoming Caerphilly by-election is more than just a local political contest—it’s a litmus test for Labour’s standing in Wales, as the party faces growing disillusionment among its once-reliable voter base.
A YouGov poll from September underscores the scale of the problem. Just 37% of those who backed Labour at the last general election say they are likely to do so again in next year’s Senedd election. Even more concerning for the party: 34% now plan to vote for Plaid Cymru. This is more than a blip—it signals a deepening erosion of trust in Labour’s Welsh leadership, which could prove costly in Caerphilly on 23rd October, and into next year.
While Reform UK’s popularity continues to grow across the UK, the YouGov data suggests Labour’s decline in Wales isn’t primarily about Farage. Rather, it reflects frustration with a party that has led the Senedd since its creation. From persistent issues in healthcare and education to the struggles of the national party and controversies during Vaughan Gething’s leadership, voters appear increasingly ready to hold Labour to account in Wales.
Crucially, even among those who still plan to vote Labour in a general election, only 78% say they would do so in the Senedd elections. This suggests that while some voters may trust Labour at Westminster, fewer believe it still deserves to govern in Cardiff Bay.
The poll also reveals a significant bloc of undecided voters, many of whom previously backed Labour.
So, the real test in historically safe Caerphilly is whether the party can win back these wavering supporters, or whether it will be Plaid Cymru or Reform that consolidates the current anti-Labour sentiment.
These undecided voters will help determine whether Labour is heading for bad Senedd election in 2026—or an awful one.
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