Labour MP Kate Hoey has announced she will not seek re-election after 30 years as the member for Vauxhall.
She caused controversy within her party during the 2016 EU referendum as a leading pro-Brexit figure, campaigning alongside Nigel Farage.
Ms Hoey said she would not run again after the 2015 election, but then stood when the 2017 snap-election was called.
However, in July 2018, she lost a no confidence vote in her local party – a staunchly Remain London constituency.
The London Borough of Lambeth, which includes Ms Hoey’s constituency, voted 78.6% to Remain in the EU – the highest proportion of Remain voters aside from Gibraltar.
In a letter to constituents, she said she will carry on until the next general election “with energy, honesty and integrity”, adding: “I will, of course, continue every single day to give all my help to constituents in Vauxhall and campaign for policies that make life better for residents”.
The Jeremy Corbyn-supporting campaign group Momentum welcomed her decision, accusing her of being a “no deal supporting, anti gay rights, fox hunting advocate”.
The group tweeted: “She couldn’t be more out of step with her Vauxhall constituents, and we look forward to backing a Corbyn supporting, socialist candidate in an open selection.”
Labour MPs have until the end of the day to inform their local parties whether they plan to stand again at the next election.
While the next election is not scheduled to take place until May 2022, many believe there could be a snap poll in the autumn if there is deadlock between the next prime minister and Parliament over a no-deal Brexit.
Former shadow education secretary Stephen Twigg has said he will not contest his Liverpool West Derby seat.
Mr Twigg, the chair of the Commons international development committee, has held the seat since 2010 – having previously represented Enfield Southgate between 1997 and 2005.
And long-serving Ealing North MP Stephen Pound is also to leave the Commons, having represented the west London constituency since 1997.