[6][7][8] The incumbent Labour MP Jamie Reed announced his intention to resign on 21 December 2016[9] in order to become the new Head of Development & Community Relations at Sellafield Ltd,[10] where he had worked before becoming a politician.

Although Reed supported remaining within the European Union, his constituency voted to leave in the June 2016 EU referendum.

Chris Hanretty, a Reader in Politics at the University of East Anglia, estimated through a demographic model that in Copeland, 60% of voters voted 'Leave'.

[18] The short list to be Labour's candidate, announced on 12 January, had included Barbara Cannon, a former Borough and County Councillor, Rachel Holliday, founder of Calderwood House hostel, and Troughton.

[11] The UK Independence Party's (UKIP) West Cumbria branch selected Fiona Mills as their candidate, a local National Health Service (NHS) worker, member of UKIP's National Executive Committee and county chairwoman, who had stood as the party's candidate in Carlisle in the 2015 general election.

Copeland borough and Whitehaven town councillor Michael Guest announced his candidacy on 31 January, saying he was aiming to represent people "dissatisfied with party politics".

[36] Whitehaven market stallholder Roy Ivinson, who also submitted nomination papers, had previously stood for seats in the area on a platform of stopping global warming.

[37] An early issue in the campaign was plans to downgrade maternity services at West Cumberland Hospital in Whitehaven.

[27] Trade unions claimed that government cuts to Sellafield's employee pension scheme could "threaten the Conservatives' chances of winning the by-election".