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When Wales votes in next year’s Senedd elections, things will look very different.

After next May’s elections, the number of Senedd Members will increase from 60 to 96 – with a whole new way of electing our representatives being introduced, as well as a redrawing of the political map.

Next year, Wales will be divided up into 16 ‘super constituencies‘, each electing six candidates to represent them in Cardiff Bay.

Voters living in Caerphilly County Borough will find themselves in one of two constituencies – either Blaenau Gwent Caerffili Rhymni, or Casnewydd Islwyn.

Who is standing in Casnewydd Islwyn?

The Casnewydd Islwyn seat covers Newport and a chunk of Caerphilly County Borough.

It includes the Caerphilly Council wards of Abercarn, Argoed, Blackwood, Crosskeys, Crumlin, Newbridge, Penmaen, Risca East, Risca West, and Cefn Fforest (but not Pengam).

Both Welsh Labour and Plaid Cymru have published a full list of candidates for the seat, while the Welsh Conservatives, Liberal Democrats, and the Greens have so far revealed only some of their candidates.

Reform are expected to reveal their candidates at a later date.

Islwyn MS Rhianon Passmore is second on the list for Labour, with Newport West MS Jayne Bryant securing top spot. Peredur Owen Griffiths, who currently represents the South Wales East region, tops Plaid’s list for the seat.

Natasha Asghar, who also represents South Wales East, is number one on the Welsh Conservative list.

Other candidates include former Newbridge councillor Lyn Ackerman and Blackwood Town Council deputy mayor Rhys Mills, both of Plaid Cymru. Another candidate is Mike Hamilton, a former Lib Dem general election candidate who also stood for his party at last year’s police and crime commissioner election.

Candidates revealed so far

Liberal Democrats

1. Mike Hamilton
2. John Miller

Plaid Cymru

1. Peredur Owen Griffiths
2. Lyn Ackerman
3. Rhys Mills
4. Josh Rawcliffe
5. Jonathan Clark

Reform UK

• No candidates announced yet

Wales Green Party

1. Rachel Roberts

Welsh Conservatives

1. Natasha Asghar
2. Toby Jones
3. Jake Enea

Welsh Labour

1. Jayne Bryant
2. Rhianon Passmore
3. Chris Carter
4. Rhian Howells
5. Julie Sangani
6. Stephen Marshall
7. David Chinnick

How will the 2026 Senedd election differ?

Currently, Wales uses an additional member system – a mix of proportional representation and the first-past-the-post system used in Westminster elections.

Forty constituency Senedd Members are elected via first past the post and a further 20 are elected to represent five regions via party lists.

But from 2026 voters will receive one ballot rather than two, with first past the post scrapped and all members elected via a full form of proportional representation.

Wales will use “closed lists”, which will see people voting for parties rather than specific candidates, despite experts describing the new system as dangerous.

Political parties will decide the order of candidates on lists unlike under a flexible-list system or the single transferable vote which would give the electorate a say.

The D’Hondt method, a formula to apportion seats based on votes, will continue to be used over the Sainte-Lague system which would benefit smaller parties.