Casnewydd Islwyn (Senedd constituency)

Casnewydd Islwyn
County multi-member constituency for the Senedd
Boundary of Casnewydd Islwyn in Wales
Principal areas	Caerphilly County Borough Newport
Preserved county	Gwent
Major settlements	Abercarn, Blackwood, Caerleon, Newbridge, Newport, Risca
Future County multi-member constituency
Created	2026
Seats	6
Created from	UK Parliament boundaries: Newport East Newport West and Islwyn Previous Senedd constituencies: Islwyn Newport East Newport West Previous Senedd region: South Wales East

Casnewydd Islwyn ( Welsh for ' Newport [and] Islwyn ') is a proposed six-member constituency of the Senedd (Welsh Parliament; Welsh : Senedd Cymru) to be used for the 2026 Senedd election.

It was proposed following the 2026 review of Senedd constituencies, and will be a pairing of the two UK Parliament constituencies of Newport East and Newport West and Islwyn. It is to have a Welsh-only name.

Boundaries

A Senedd constituency comprising the boundaries of the UK Parliament constituencies of Newport East and Newport West and Islwyn, has been proposed by the Democracy and Boundary Commission Cymru for the 2026 election to the Senedd (Welsh Parliament; Senedd Cymru). It was initially proposed using the name Newport and Islwyn in September 2024, ^[1] but was renamed to Casnewydd Islwyn in December proposals with most constituencies using Welsh-only names. ^[2] The Welsh-only name and boundaries were confirmed in the commission's final recommendations in March 2025. ^[3]

It encompasses the entire of the principal area (county borough) of Newport and parts of Caerphilly County Borough in South Wales. The constituency is to be established by 2026, following the passing of the Senedd Cymru (Members and Elections) Act 2024. The act legislates electoral reform of the Senedd to create 16 larger "super constituencies", pairing the 32 UK Parliament constituencies in Wales, and using a new fully proportional voting system, with each constituency electing six Members of the Senedd (MSs) rather than one previously. ^[1]

Elections

Elections in the 2020s

Next Senedd election: Casnewydd Islwyn

Party		Candidate	Votes	%	±%
Majority
Turnout
Registered electors
	win (new seat)

References

1. Hayward, Will (2 September 2024). "The full details of Wales' 16 new constituencies for Senedd elections". Wales Online. Retrieved 28 February 2025.
2. "Proposed Senedd constituency names divides opinion". ITV News . 17 December 2024.
3. Price, Emily (11 March 2025). "New Senedd 'super constituencies' confirmed". Nation.Cymru. Retrieved 11 March 2025.