Jamie Reed is to quit as MP for Copeland in Cumbria at the end of January, moving on to become head of development and community relations at the Sellafield nuclear plant in his constituency.
The Labour MP, who has held the constituency since 2005, said it was the “hardest decision of my life”.
Reed told the Guardian that his departure had “absolutely nothing to do with Jeremy Corbyn”.
After 12 years in Parliament, I'm leaving. Hardest decision of my life and a privilege beyond compare. Thank you all. pic.twitter.com/ARhmwK2XJb— Jamie Reed (@JamieFonzarelli) December 21, 2016
Conservative Party chairman Patrick McLoughlin said in a statement that he was sorry to see Reed leaving parliament.
He added: “It is a sorry state of affairs when talented Members of Parliament like him no longer feel comfortable representing Jeremy Corbyn’s Labour Party – a divided party run by a leader who opposes Trident and wants to dismantle our Armed Forces.
“We look forward to the by-election, and the opportunity to set out how the Conservatives are building a country that works for everyone, not just the privileged few.”
In last year’s general election, Reed claimed 42 per cent of the vote for Labour, coming ahead of the Tories on 36 per cent and Ukip on 16 per cent.