Overview
- Polling of 1,232 adults conducted September 4–10 shows Plaid on 30%, Reform on 29%, Labour on 14%, Conservatives on 11%, and Lib Dems and Greens on 6% each.
- Seat projections for the new 96‑member Senedd map Plaid and Reform to the mid‑to‑high 30s, with Labour around 11–12 seats under the more proportional system.
- Analysts say Labour is losing support primarily to Plaid and the Greens, with some defections to Reform, while Reform’s gains are driven largely by former Conservative voters.
- Plaid leader Rhun ap Iorwerth warns Reform could threaten devolution after comments from its MS about questioning the Senedd’s value, as Reform consolidates right‑of‑centre backing.
- YouGov also finds Reform leading Westminster vote intention in Wales for the first time, and parties are treating the October 23 Caerphilly by‑election and the 2026 Senedd vote as key tests for leadership and alliances.