The Green party in the constituency of Oxford East has chosen gay rights activist Peter Tatchell to contest the seat at the next general election.
The seat has been held by Labour MP Andrew Smith since 1987.
Mr Smith was Chief Secretary to the Treasury from 1999 and Secretary of State for Work and Pensions from 2002. He left the Cabinet in 2004.
At the 2005 general election he retained Oxford East but saw his majority cut by 90% in a swing to the Liberal Democrats.
The Greens came fourth with 4.3% of the vote.
Oxford East has been subject to boundary changes, with most of the world-renowned Oxford colleges now forming part of the constituency.
It will be Mr Tatchell’s first Westminster campaign since the infamous Bermondsey by-election in 1983.
On that occasion, a split in the Labour party and a blatantly homophobic campaign by the Liberals saw the safe Labour seat in south-east London go to Simon Hughes, now President of the Lib Dems.
In 2006 it was revealed that Mr Hughes is himself bisexual.
Mr Tatchell told the BBC: “The people of Oxford have an opportunity to make history by electing Britain’s first Green MP.
“I plan to start living part-time in the constituency and to get immersed in local community campaigns.”
In 1990 Mr Tatchell sought the Labour nomination in the Hampstead and Highgate constituency but was beaten by double Oscar-winning actress Glenda Jackson.
“He is going to raise the game for the whole party,” Green Party spokesman Derek Wall told the BBC.
“I think his selection will be seen as a real turning point, making the party more serious, more professional and more focused on issues of justice.”