Image copyright PA Image caption Ruth Jones with Labour leader Jeremy Corbyn during the campaign
The polls have closed in the Newport West by-election.
The seat in south east Wales became vacant following the death of veteran Labour MP Paul Flynn in February.
A total of 11 candidates are standing and a result is expected in the early hours of Friday.
Labour are defending a 5,658 majority over the Conservatives at the 2017 general election. Mr Flynn had held the seat since 1987.
Image copyright BBC/PA/Parties Image caption The candidates include (top left and clockwise) Ryan Jones, Lib Dem; Matthew Evans, Conservative; Neil Hamilton, UKIP, Jonathan Clark, Plaid and Amelia Womack, Green
Jonathan Clark, Plaid Cymru
June Davies, Renew
Matthew Evans, Conservative
Neil Hamilton, UKIP
Ruth Jones, Labour
Ryan Jones, Liberal Democrat
Ian McLean, Social Democratic Party
Hugh Nicklin, For Britain
Richard Suchorzewski, Abolish the Welsh Assembly Party
Phillip Taylor, Democrats and Veterans
Amelia Womack, Green Party of England and Wales
Image copyright Getty Images Image caption Plaid Cymru canvassing on Thursday in Newport West
Image copyright Getty Images Image caption Annabel Mullin, leader of the Renew Party in the constituency on Thursday
One of the major issues has been whether the M4 relief road should be built around Newport, although the decision is devolved.
It is part of a wider Newport local area which saw 56% vote for Brexit.
Labour candidate Ruth Jones was born and brought up in the constituency and is a trained physiotherapist turned full-time trade union official for the Chartered Society of Physiotherapy. She was a candidate in the 2015 and 2017 general elections in Monmouth.
The Conservative candidate is Matthew Evans,