The Green Party’s only MP Caroline Lucas has announced that she will not contest the next election.
Ms Lucas, who had two spells as leader of her party, said her role in Parliament meant she had “struggled to spend the time I want” on the crises facing the environment.
“I have therefore decided not to stand again as your MP at the next election,” she told constituents in a letter.
The 62-year-old 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.
In comments first reported by The Argus newspaper in Brighton, Ms Lucas said it had been the “privilege of my life to serve this extraordinary constituency and community”.
But she 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.
“And the truth is, as these threats to our precious planet become ever more urgent, I have 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.”
Ms Lucas was Green Party leader between 2008 and 2012 before returning for a second stint at the helm, this time co-leading the party with Jonathan Bartley for two years from September 2016.
The Green Party’s co-leader Carla Denyer heralded Ms Lucas as a “force of nature” when paying tribute to her activism.
She said: “Caroline’s impact on politics in this country cannot be overstated.”
Joint leader Adrian Ramsay said the party, which made gains at the local elections in England last month, would be focused on electing new representatives to replace Ms Lucas, who remains the only Green candidate to have made it to the green benches.
“Having MPs who are genuinely dedicated to standing up for the climate and nature could not be more important than it is right now and that’s why we are striving to get more Green MPs elected at the next general election so that we can build on Caroline’s achievements,” he said.
Ms Lucas joins a growing band of senior elected politicians who have declared that they will step down at the next election, which is expected to be contested next year.
More than 50 MPs have announced an end to their Commons’ careers, including former SNP Westminster leader Ian Blackford, Conservative former deputy prime minister Dominic Raab and former deputy Labour Party leader Margaret Beckett.