Plaid Cymru is projected to emerge as the largest party in the Senedd for the first time, according to YouGov’s final MRP model for ITV Cymru Wales ahead of the 2026 election.
The projection points to a major shift in Welsh politics, with Labour set for its worst major election result in Wales in more than a century and Reform UK making substantial gains across the country.
Under YouGov’s central estimate, Plaid Cymru is projected to win 43 seats in the newly expanded 96-member Senedd, leaving the party just six seats short of an outright majority. Reform UK is projected to become the second largest party with 34 seats.
The model suggests Labour’s vote share could fall to just 12%, down 24 points compared with the 2021 election, while the Conservatives are projected to be reduced to only four seats. The Liberal Democrats are forecast to return a single member.
The Greens are also projected to make history by securing representation in the Senedd for the first time, with seats expected in both Cardiff constituencies.
YouGov’s latest model is based on responses from more than 4,600 adults in Wales gathered between 25 April and 4 May.
The findings place Plaid Cymru leader Rhun ap Iorwerth in pole position to become Wales’ next first minister.
For Plaid Cymru and Reform UK, the projected results would mark significant gains compared with the 2021 election. Under the current electoral system, Plaid Cymru would have secured 24 seats in 2021, while Reform UK won just 1% of the vote and no seats.
YouGov said Plaid Cymru had made small gains during the final stages of the campaign, largely at the expense of the Greens, after an earlier mid-April model suggested a much tighter race between Plaid Cymru and Reform UK.
Despite the headline projection, YouGov stressed that the outcome remains highly competitive due to the new D’Hondt voting system, with some seat allocations described as being “on a knife-edge”.
Plaid Cymru’s projected range stretches from 36 to 48 seats, while Reform UK’s range sits between 31 and 41 seats. Reform UK is projected to emerge as the largest party in 13% of simulations.
The projected collapse in Labour support represents one of the biggest political shifts in modern Welsh electoral history.
Labour, which has won every devolved election since the Senedd was established and topped the poll in Wales at every Westminster election since 1922, is forecast to win just 12 seats.
The model also projects that Labour will fail to finish first in any of the Senedd’s 16 constituencies and could fail to win any seats at all in four constituencies.
One of those constituencies is Ceredigion Penfro, where current first minister Eluned Morgan tops Labour’s list of candidates, raising the possibility that she could lose her seat.
Meanwhile, the Conservatives are projected to fall from a notional 26 seats in 2021 to just four seats in the new Senedd. Such a result would leave the party below the five-seat threshold required to form an official political group, limiting its ability to chair committees and question ministers.
The Liberal Democrats are also forecast to remain below that threshold, with Jane Dodds projected to retain the party’s only seat in the Brycheiniog Tawe Nedd constituency.
While Plaid Cymru is projected to finish ahead overall, YouGov’s modelling suggests the party may still require Labour’s support to form a stable majority administration. Together, Plaid Cymru and Labour are projected to pass the 49-seat majority threshold in 89% of simulations.
