Senedd Cymru 2026 · Scaffold forecast
96 seats, new closed-list PR system
First public estimate under the Senedd Cymru (Members and Elections) Act 2024. 16 super-constituencies × 6 list seats.
refresh_required_by: 2026-05-01) and the 14-day Wikipedia rolling-average parser
hasn't found a fresh Welsh-only field in a month. There are also no prior election results on
the new 16 super-constituency boundaries to anchor a per-area forecast, the projection
applies a single Wales-wide swing uniformly. Treat the numbers below as illustrative
until we publish a calibrated v1 with current Beaufort/YouGov Wales/ITV Wales fields and the
2024 GE Welsh results re-aggregated to the new super-constituencies.
Methodology in brief
This is the first Senedd election under the new geography, there are no prior election results on these super-constituency boundaries to anchor a per-area forecast. The numbers below apply Welsh-wide vote intention uniformly to each of the 16 super-constituencies and run d'Hondt allocation in each one independently. Per-area geographic differentiation, using 2024 general election Welsh constituency-level results aggregated to the new super-constituency pairings, is a planned upgrade.
The intervals below are wider than the local-elections forecast. 5 percentage points of per-party noise built into the bootstrap, to reflect this new-system uncertainty. Treat the numbers as a first estimate, not a final prediction.
Wales-wide projection
Predicted seat totals (96 seats)
| Party | Central | P10 | P50 | P90 |
|---|---|---|---|---|
| Plaid Cymru | 37 | 24 | 36 | 44 |
| Reform UK | 33 | 27 | 32 | 43 |
| Labour | 11 | 0 | 11 | 16 |
| Green Party | 7 | 1 | 8 | 17 |
| Conservative | 7 | 1 | 6 | 16 |
| Liberal Democrats | 1 | 0 | 2 | 7 |
| Independent | 0 | 0 | 0 | 0 |
| Heritage Party | 0 | 0 | 0 | 0 |
| Other | 0 | 0 | 0 | 0 |
| Socialist Labour Party | 0 | 0 | 0 | 0 |
| Climate Party | 0 | 0 | 0 | 0 |
| The Official Monster Raving Loony Party | 0 | 0 | 0 | 0 |
| Libertarian Party | 0 | 0 | 0 | 0 |
| Workers Party of Britain | 0 | 0 | 0 | 0 |
| Communist Party of Britain | 0 | 0 | 0 | 0 |
| Abolish The Welsh Assembly Party | 0 | 0 | 0 | 0 |
| Trade Unionist and Socialist Coalition | 0 | 0 | 0 | 0 |
| Women's Equality Party | 0 | 0 | 0 | 0 |
| Propel | 0 | 0 | 0 | 0 |
| True & Fair Party | 0 | 0 | 0 | 0 |
| UK Independence Party (UKIP) | 0 | 0 | 0 | 0 |
Super-constituencies
16 super-constituencies × 6 seats
| Super-constituency | Top predicted parties (central allocation) |
|---|---|
| Afan Ogwr Rhondda | Reform UK 3 Plaid Cymru 2 Labour 1 |
| Bangor Conwy Môn | Plaid Cymru 3 Reform UK 2 Conservative 1 |
| Blaenau Gwent Caerffili Rhymni | Plaid Cymru 2 Reform UK 2 Labour 1 Green Party 1 |
| Brycheiniog Tawe Nedd | Reform UK 2 Plaid Cymru 2 Liberal Democrats 1 Conservative 1 |
| Caerdydd Ffynnon Taf | Reform UK 2 Plaid Cymru 2 Labour 1 Green Party 1 |
| Caerdydd Penarth | Reform UK 2 Plaid Cymru 2 Labour 1 Green Party 1 |
| Casnewydd Islwyn | Reform UK 2 Plaid Cymru 2 Labour 1 Green Party 1 |
| Ceredigion Penfro | Plaid Cymru 3 Reform UK 2 Conservative 1 |
| Clwyd | Reform UK 2 Plaid Cymru 2 Labour 1 Conservative 1 |
| Fflint Wrecsam | Reform UK 2 Plaid Cymru 2 Labour 1 Conservative 1 |
| Gwynedd Maldwyn | Plaid Cymru 4 Reform UK 2 |
| Gŵyr Abertawe | Reform UK 2 Plaid Cymru 2 Labour 1 Green Party 1 |
| Pen-y-bont Bro Morgannwg | Reform UK 2 Plaid Cymru 2 Labour 1 Conservative 1 |
| Pontypridd Cynon Merthyr | Reform UK 2 Plaid Cymru 2 Labour 1 Green Party 1 |
| Sir Fynwy Torfaen | Reform UK 2 Labour 1 Conservative 1 Green Party 1 Plaid Cymru 1 |
| Sir Gaerfyrddin | Plaid Cymru 4 Reform UK 2 |
Inputs
Welsh 2024 general election baseline: Wales-wide vote share aggregated across the 32 Welsh Westminster constituencies (Labour 36.6%, Reform UK 16.9%, Conservative 18.2%, Plaid Cymru 14.9%, Lib Dem 6.7%, Green 4.3%).
Welsh polling: Auto-refreshed daily as the Wikipedia rolling 14-day average of every Welsh poll (current values shown on the About page).
Method: Per super-constituency. 6 seats allocated by d'Hondt highest-averages over Welsh-wide current polling. Bootstrapped with 2,000 samples and 5pp per-party noise to produce the high–low range.