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The 2026 Senedd election, scheduled for Thursday 7 May, is set to be one of the most consequential contests in modern Welsh political history.

A major overhaul of the electoral system has transformed the landscape ahead of polling day. The Welsh government’s move away from the mixed system – combining constituency-based first-past-the-post seats with regional list representation – to a fully proportional, region-based model is expected to end single-party majorities in the Senedd. An increase in the number of members has further complicated direct comparisons with previous elections.

Recent electoral evidence points to a fragmented and highly competitive race. In a by-election last year, Welsh Labour came third in its traditionally safe seat of Caerphilly. Analysts noted a split in the working-class vote, driven by concerns over the cost of living and immigration. Both Plaid Cymru, which won the seat, and Reform UK drew support from different segments of Labour’s traditional base.

The polls since then have all but confirmed the Caerphilly narrative: Labour far behind, with Plaid and Reform fighting it out for first.

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Across Wales, Labour’s position appears to have weakened significantly. Projections indicate the party could be on course for one of its poorest performances in over a century. Its gains in North Wales at the 2024 general election now look vulnerable, while in parts of South Wales – including around Cardiff – emerging competition from smaller parties has added further uncertainty.

The Green Party of England and Wales, while historically underrepresented in the Senedd, is forecast in some scenarios to secure its first members under the new proportional system. Meanwhile, Welsh Conservatives are also expected to face losses, reflecting a broader reshaping of the political balance.

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According to the Britain Predicts model, Plaid Cymru is best placed to emerge as the largest party, potentially leading the Welsh government for the first time. A nationalist party heading the administration in Cardiff Bay would mark a historic shift. However, coalition-building will be essential, as no party is expected to command a majority. Both progressive and centre-right alliances remain arithmetically possible.

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Seat-by-seat forecast

At the constituency and regional level, the projections point to a highly competitive and unpredictable map. Many areas will be won by tight margins.

The Britain Predicts model applies the same methodology that underpinned its 2024 forecasts, combining demographic data, national polling trends and historical patterns of over- and under-performance. It distinguishes between more volatile “swing” voters and those with entrenched party loyalties – though the latter appear to be weakening. The model does not incorporate insider assumptions or subjective adjustments. Instead, it offers a transparent, data-driven projection of how votes may translate into seats under the new system.

Structural reform, shifting voter behaviour and a fragmented party system together mean the 2026 Senedd election is poised to redefine Welsh politics – regardless of which party ultimately emerges on top.

[Further reading: Britain can’t afford to be middle class anymore]

Source link www.newstatesman.com