Former Green Party leader Caroline Lucas is stepping down at the next general election.
In a letter sent to her Brighton Pavilion constituents, Ms Lucas said it had been the “privilege of my life to serve this extraordinary constituency and community”.
She said the “threats to our precious planet” had become “ever more urgent”, but that her role in parliament as the Green Party’s only MP meant she had “struggled to spend the time I want on these accelerating crises”.
“I have therefore decided not to stand again as your MP at the next election,” she said.
Ms Lucas, 62, was elected as the MP for Brighton Pavilion at the 2010 general election, becoming the first Green Party candidate to be elected to the House of Commons.
Her majority has increased at every election since, with voters returning her to parliament with a majority of almost 20,000 in 2019.
The Green Party praised her as a “force of nature” following her announcement.
Co-leader Carla Denyer said: “Caroline’s impact on politics in this country cannot be overstated: she truly is a force of nature and has been an extraordinary servant of the people of Brighton Pavilion as well as the Green Party. We are so proud of her achievements.
“Whether securing significant policy changes, shaping the conversation or modelling a different way of doing politics, Caroline demonstrates how essential it is to have green voices in UK politics.”
Joint leader Adrian Ramsay added: “Very few politicians can claim to have changed the course of the national debate in the way Caroline has. She has brought so much to us as a party, shown real integrity in her work and added a crucial dimension to our democracy in this country.”
He said the party is now “striving to get more Green MPs elected at the next general election so that we can build on Caroline’s achievements”.
In her letter, Ms Lucas said her focus on being “first and foremost a good constituency MP” meant she had “not been able to focus as much as I would like” on climate concerns.
She said: “I’ve done everything possible to help wherever I can and always worked to ensure that people feel heard, that their concerns matter, and that they are not alone.
“But the intensity of these constituency commitments, together with the particular responsibilities of being my party’s sole MP, mean that, ironically, I’ve not been able to focus as much as I would like on the existential challenges that drive me – the nature and climate emergencies.”