Plaid Cymru set to be largest party in Wales after Senedd 2026 election, according to latest poll

Ben Birchall/PA Wire/PA Images
The data shows Plaid Cymru in the lead, closely followed by Reform UK, with Labour support dropping. Credit: PA Images

Plaid Cymru is set to be the largest party in Wales, closely followed by Reform UK, after the 2026 Senedd election, according to a new YouGov poll.

The data shows Plaid in the lead with 33% of the Senedd voting intention, closely followed by Reform at 30%, with Labour vote share projected to drop to 10%.

It means Plaid is on course to win the largest number of seats in the Senedd after the election on 7 May, according to the poll of 2,500 adults in Wales. The poll has been conducted by YouGov for Cardiff University.

It would represent a landmark change in Welsh politics, as Labour has run the government in Wales in all the 26 years of devolution.

Senedd voting intention (excluding non-voters and 'don’t knows'), according to YouGov:

  • Plaid Cymru 33%

  • Reform UK 30%

  • Labour 10%

  • Conservatives 10%

  • Green 9%

  • Lib Dem 6%

  • Other 3%

The Conservatives, Green Party and Liberal Democrats are predicted to win a small number of seats in the expanded Senedd, which after May will have 96 members - up from 60. The voting system and constituencies will also be changing.

FM Eluned Morgan says her aim is to be "the lead partner in government" following next year's Senedd Election in May.

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If the trends shown in the poll are repeated at the ballot box, Dr Jac Larner of the Wales Governance Centre predicts the following Senedd seat projections:

  • Plaid Cymru - 39

  • Reform UK - 34

  • Labour - 10

  • Conservatives - 6

  • Green - 4

  • Lib Dem – 3

Plaid Cymru's projected vote share has increased by 3%, Reform's has risen by 1% and Labour support has dropped by 4% since ITV Wales' YouGov/Barn Cymru Senedd voting intention poll in September 2025.

The poll saw 2,500 adults in Wales quizzed online between 28 November and 10 December.

In October Plaid's Lindsay Whittle trounced Labour in the Caerphilly by-election, showing an upward trajectory over Welsh Labour. Credit: Matthew Horwood

Plaid say party can 'deliver the new leadership Wales deserves'

A Plaid Cymru spokesperson said: "Coming so soon after our Caerphilly by-election win, this poll shows the momentum is firmly with Plaid Cymru and that next year’s election is shaping up to be a straight choice for Wales’ future.

"After years in power, Labour have given up on Wales. People are tired of broken promises and being taken for granted and yearning for something new: fairness, ambition, and a government that finally puts Wales first.

"At the next election, the people of Wales face two choices of two futures. One is a party rooted in Wales, focused on improving our NHS, public services, and helping families with the cost of living. The other is a billionaire-backed party that would privatise our NHS and take Wales backwards.

"This is a two-horse race, and only Plaid Cymru brings a positive vision, can stop Reform and deliver the new leadership Wales deserves."

Reform UK: Party will be 'fighting to restore common sense to Welsh politics'

A Reform UK Wales spokesperson said: “It’s clear to everybody here in Wales that the next Senedd election will be a two-horse race between Reform and Plaid.

“With Plaid, Wales will get more of the same extreme policies that we’ve had from Plaid and Labour working in tandem in Cardiff Bay. Meanwhile, Reform will be fighting to restore common sense to Welsh politics, and to deliver real change for our communities here in Wales.”

Welsh Labour 'determined to earn back voters' trust'

A Welsh Labour source said: “There will be many polls before May. This doesn’t mean this is where we’ll be by election day. Welsh Labour is focused on protecting jobs, bringing down waiting lists, supporting our communities. This is what makes a difference to everyone’s everyday lives. We know we’ve got work to do, but we’re determined to earn back the trust that voters have put in us before.”

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