A new poll has Labour staring down a once-unthinkable rout in its traditional heartland of Wales, with the party projected to plummet to a distant third place in the 7 May Senedd election.
YouGov’s first multilevel regression and post-stratification (MRP) model of the 2026 Welsh Parliament contest shows Plaid Cymru on course to win 43 seats in the newly expanded 96-member Senedd, just six short of an outright majority.
That would mark the first time since devolution in 1999 that the Welsh nationalists have finished as the largest party, catapulting leader Rhun ap Iorwerth into pole position to become the next first minister of Wales.
Labour, which has dominated Welsh politics for more than a century and won every devolved election to date, is projected to win just 12 seats – a staggering notional loss of 32 seats from the adjusted 2021 results. Its projected vote share collapses to 13%, down 23 points on 2021.
The rout pushes Keir Starmer’s party into third place behind a surging Reform UK, which is on track for 30 seats and 27% of the vote, an massive gain from just 1% at the last Senedd election.
The Greens are also set for a breakthrough, winning 10 seats on 12% of the vote, while the Conservatives are projected to be almost wiped out with just one seat (a notional loss of 25) on a miserable 7% share. The Liberal Democrats are forecast to win zero seats.
Here’s the full central seat projection from YouGov’s MRP:
- Plaid Cymru: 43 seats (+19)
- Reform UK: 30 seats (+30)
- Labour: 12 seats (−32)
- Greens: 10 seats (+10)
- Conservatives: 1 seat (−25)
- Liberal Democrats: 0 seats (−2)
Corresponding vote shares:
- Plaid Cymru: 33% (+12)
- Reform UK: 27% (+26)
- Labour: 13% (−23)
- Greens: 12% (+8)
- Conservatives: 7% (−18)
- Liberal Democrats: 5% (+1)
The projections come under Wales’s new proportional representation system, which allots six Members of the Senedd (MSs) per constituency and is designed to more closely align seats with vote share, though parties with stronger geographic concentration still enjoy a slight edge.
Plaid Cymru would fall six seats short of the 49 needed for a majority but would have clear paths to power: a coalition with Labour would deliver 55 seats, a comfortable majority, while teaming up with the Greens would yield 53. The party has previously signalled openness to governing as a minority administration.
YouGov described the Tory result as “nearing existential” for the Welsh Conservatives, who would be reduced to a single seat in the northeast. Labour’s projected collapse would leave it without representation across vast swathes of the country, from Llanelli in the south to Llandudno in the north.
The poll lands as a fresh headache for Prime Minister Keir Starmer, whose party has already faced tough local election tests and is grappling with Reform UK’s growing national momentum. A Plaid-led government in Cardiff Bay would further complicate Labour’s grip on the UK’s devolved nations at a time when the party is already navigating tensions in Scotland.
YouGov noted that while Plaid Cymru is the clear favorite in its central estimate, the model leaves room for volatility.
Plaid’s vote share could dip as low as 28%, while Reform’s could reach 31%, meaning it remains theoretically possible, though unlikely, for Reform to edge ahead on votes.
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