Y gwahaniaeth rhwng diwygiadau o "Gorllewin Casnewydd (etholaeth seneddol)"

 
Bu farw [[Paul Flynn]] ar [[17 Chwefror]] [[2019]] a chynhaliwyd isetholiad i ganfod olynydd iddo ar [[4 Ebrill]] [[2019]]
{{Dechrau bocs etholiad |
 
{{Election box begin|titleteitl=Isetholiad Gorllewin Casnewydd 2019 2019}}
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{{Election box candidate with party link
{{Bocs ymgeisydd etholiad gyda dolen plaid
|partyplaid=Plaid Cymru
|candidateymgeisydd=Jonathan Clark
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{{Election box candidate with party link
|partyplaid=Renew Party
|candidateymgeisydd=June Davies
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{{Election box candidate with party link
|plaid=Y Blaid Geidwadol (DU)
|party=Conservative Party (UK)
|candidateymgeisydd=Matthew Evans
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{{Election box candidate with party link
|plaid=Plaid Annibyniaeth y Deyrnas Unedig
|party=UK Independence Party
|candidateymgeisydd=[[Neil Hamilton]]
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{{Bocs ymgeisydd etholiad gyda dolen plaid
{{Election box candidate with party link
|plaid=Y Blaid Lafur (DU)
|party=Labour Party (UK)
|candidateymgeisydd=Ruth Jones
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{{Bocs ymgeisydd etholiad gyda dolen plaid
{{Election box candidate with party link
|plaid=Y Democratiaid Rhyddfrydol
|party=Liberal Democrats (UK)
|candidateymgeisydd=Ryan Jones
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{{Bocs ymgeisydd etholiad gyda dolen plaid
{{Election box candidate with party link
|partyplaid=Y Blaid Ddemocrataidd Gymdeithasol (DU, 1990)
|candidateymgeisydd=Ian McLean
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{{Bocs ymgeisydd etholiad gyda dolen plaid
{{Election box candidate with party link
|partyplaid=For Britain
|candidateymgeisydd=Hugh Nicklin
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{{Bocs ymgeisydd etholiad gyda dolen plaid
{{Election box candidate with party link
|partyplaid=Diddymu Cynulliad Cymru
|candidateymgeisydd=Richard Suchorzewski
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{{Bocs ymgeisydd etholiad gyda dolen plaid
{{Election box candidate with party link
|partyplaid=Democratiaid a chyn-filwyr
|candidateymgeisydd=Philip Taylor
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{{Bocs ymgeisydd etholiad gyda dolen plaid
{{Election box candidate with party link
|plaid=Plaid Werdd Cymru a Lloegr
|party=Green Party of England and Wales
|candidateymgeisydd=[[Amelia Womack]]
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{{Bocs mwyafrif etholiad|
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{{Bocs y nifer a bleidleisiodd mewn etholiad|
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{{Diwedd bocs etholiad}}
 
{{Dechrau bocs etholiad | teitl=[[Etholiad cyffredinol y Deyrnas Unedig, 2017|Etholiad cyffredinol 2017]]: Etholaeth: Gorllewin Casnewydd<ref>Daily Post 10 Mehefin 2017 ''How Wales Voted - results in detail''</ref>