Birmingham MP Gisela Stuart has announced she is quitting.
Mrs Stuart, Labour MP for Birmingham Edgbaston, has told her local party she is standing down after 20 years in the House of Commons.
She said: "After 22 years of campaigning and 20 years of having had the privilege of being the MP for this diverse, forever surprising and wonderful marginal seat I know when it is time to stand down and pass on the baton."
Her surprise win in the 1997 general election symbolised the success of the Labour Party under Tony Blair in reaching out to traditional Conservative voters. "True blue" Edgbaston had never previously had a Labour MP, and was seen as a Tory stronghold.
Mrs Stuart, a former Health Minister, made history as chair of the official "leave" campaign in the 2016 EU referendum, leading to Brexit.
But notable successes locally include leading the campaign to get Birmingham's New Street station rebuilt, and the campaign for a new Queen Elizabeth Hospital. The dramatically improved station opened in 2015, and the new hospital opened in 2010.
In a letter to Labour members in Edgbaston, she said she had decided to stand down following Theresa May's announcement that there would be an early general election on June 8.
She said: "The news yesterday of the early General Election has come as a shock to all of us. It means that we have to take decisions now which none of us thought we'd have to take 48 hours ago.
"I wanted you to hear from me that I have decided not to contest the Birmingham Edgbaston constituency at the general election in June."
Referring to the council wards that make up the constituency, she said: "Together we have done amazing things; things we never expected when I became the first 'Labour gain' of the Labour 1997 landslide as well as the first ever Labour MP for Bartley Green, Edgbaston, Harborne and Quinton.
"We won local battles, brought people together, challenged established assumptions about voters (and sometimes our own) and won elections against Tories that we didn't think were possible. But together we did it . We are Labour and our values are Labour.
"Whomever is selected as the Labour candidate will have my full backing. I will be with them and you not just in spirit but on the campaign trail. We will fight, as we always do, for every Labour vote."