Could Jeremy Corbyn hand the Senedd to Reform UK?
With just nine months until the 2026 Senedd election, political fault lines in Wales are shifting rapidly. Reform UK, led nationally by Nigel Farage, has surged in the polls and is now projected to win more seats than Labour or Plaid Cymru. But it’s not just Reform’s rise that’s redrawing the map — it’s the unexpected return of Jeremy Corbyn to frontline politics.
Corbyn, alongside Coventry South MP Zarah Sultana, has launched a new political movement aimed at challenging Labour from the left. Though the party remains unnamed, it has already attracted support from Welsh figures including former Cynon Valley MP Beth Winter and ex-PCS union leader Mark Serwotka. Their statement suggests the party will field candidates in Wales — and that could have seismic consequences.
A new voting system, a new risk
The 2026 Senedd election will be the first under Wales’ new closed list proportional representation system, with 96 Members elected across 16 larger constituencies, each returning six MSs. Voters will cast a single vote for a party, not an individual candidate. Seats will be allocated using the D’Hondt method, which favours parties with broad support across regions.
This system was designed to improve proportionality — but it also introduces new vulnerabilities. Unlike the Single Transferable Vote (STV), which allows voters to rank preferences, the closed list system offers no way to transfer votes between ideologically similar parties. That means a vote for Corbyn’s party could reduce Labour’s seat share, without boosting Plaid Cymru or other progressive parties.
If Corbyn’s party polls even 5–10%, it could cost Labour and Plaid multiple seats — handing Reform a path to power.
Reform’s rise in Llanelli, Bridgend — and beyond
Reform UK is already polling between 25–29% in Wales — ahead of Labour and Plaid Cymru in several surveys. The party has gained momentum through defections from the Conservatives, including sitting MS Laura Anne Jones, and now has 13 councillors across Wales.
Reform UK made a breakthrough in Bridgend earlier this year when 20-year-old Owain Clatworthy won a county council by-election in the Pyle, Kenfig Hill and Cefn Cribwr ward — narrowly defeating Labour by just 30 votes to claim the party’s first elected seat on Bridgend County Borough Council
In Llanelli, Reform came within 1,504 votes of unseating Labour MP Dame Nia Griffith at the 2024 general election. Gareth Beer, Reform’s candidate, finished second with over 11,000 votes — and had UKIP not stood a candidate, those votes could have tipped the seat in his favour2.
Since then, Reform has strengthened its local base. Gareth’s wife, Michelle Beer, won a Carmarthenshire County Council by-election in the Lleidi ward, defeating Labour in what had long been considered safe territory4. Gareth Beer now serves as acting chair of Reform’s Carmarthenshire branch and is widely expected to lead the party’s candidate list for the new Caerfyrddin Senedd seat.
Michelle Beer (centre) with husband Gareth Beer (right)The unintended consequences of Corbyn’s comeback
Corbyn’s new party is rooted in a radical platform: public ownership of utilities, opposition to arms sales to Israel, and a mass redistribution of wealth. It’s a message that appeals to disillusioned Labour voters, especially younger people and those active in social movements.
But in Wales, where Plaid Cymru already occupies much of the progressive space, Corbyn’s party could split the anti-Reform vote. Some left-wing voters who might otherwise back Plaid or Labour could be drawn to Corbyn’s brand of politics — especially in urban areas like Swansea and Llanelli, where Labour’s support has eroded.
Plaid Cymru has already signalled concern. Its campaign team has highlighted Zarah Sultana’s vote against devolving Crown Estate revenues to Wales — a move seen as undermining Welsh autonomy.
A challenge for Labour — and for devolution
Labour’s dominance in Wales has long relied on its ability to unite progressive voters. But internal polling suggests that fewer than half of Labour’s 2024 voters would back the party in a Senedd election today. Many are undecided — and Corbyn’s party could give them a new home.
The closed list system compounds the risk. Unlike first-past-the-post, where tactical voting can prevent vote-splitting, the new system offers no such safety net. If Corbyn’s party polls even 5–10%, it could cost Labour and Plaid multiple seats — handing Reform a path to power.
That’s not just a political headache. It’s a threat to the future of Welsh devolution. Reform UK has called for the abolition of the Senedd in the past, and its platform includes rolling back climate commitments and opposing Welsh-specific policies like free prescriptions and school meals.
What it means for South West Wales
In Swansea, Neath Port Talbot, Carmarthenshire, Pembrokeshire and Bridgend, the stakes are especially high. These areas will form part of the new larger constituencies, where six MSs will be elected per seat. That means parties need at least 13–15% of the vote to win a seat.
Reform UK is already polling above that threshold in many of these areas. If Corbyn’s party pulls votes from Labour and Plaid, Reform could win two or more seats per constituency — giving it a dominant voice in the Senedd.
For voters in South West Wales, the choice may come down to strategy. A vote for Corbyn’s party may feel principled — but under the new system, it could help elect Reform candidates who oppose the very policies Corbyn supports.
The road ahead
Corbyn’s party is still in its infancy. It hasn’t registered with the Electoral Commission, and its name, leadership structure and candidate list remain undecided. But with thousands signing up online and support growing on social media, it’s likely to be a factor in the 2026 election.
Whether it becomes a force for change or an accidental ally of Reform UK will depend on how voters respond — and whether progressive parties can find common ground before May.
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