Chloe Swarbrick, the Greens MP best known for her "OK Boomer" sledge in New Zealand's parliament, will stand to be a party co-leader.
The 29-year-old announced her candidacy on Friday to replace retiring co-leader James Shaw, joining Marama Davidson in charge of the left-wing party.
Ms Swarbrick is the sole declared candidate and considered highly likely to become co-leader.
The self-described "researched radical" said she decided to stand because her communities backed her to.
"They have asked me to stand up and put myself forward for this role," she said.
After six years supporting Labour governments with ministries outside cabinet, the Greens are in opposition in New Zealand, which has a right-leaning coalition.
Ms Swarbrick said if successful, she would use her skills to mobilise grassroots opposition to the government.
"I will challenge this government's cruel agenda and communicate the imagination, potential, and the necessary hope to mobilise for the sustainable, inspiring and inclusive Aotearoa that I see reflected every day in our communities," she said.
Ms Swarbrick is a political sensation, first running for office in 2016 when she - as a 22-year-old journalist - found the candidates for the Auckland mayoralty uninspiring and chose to join the race.
She came from nowhere to third, joining the Greens and entering parliament the following year.
In 2020 she won the Auckland Central seat in a three-cornered race with major parties National and Labour, and in 2023 became the first Greens MP to defend a seat by holding the inner-city electorate.
Ms Swarbrick has forged a reputation as an impassioned advocate for progressive ideas: curbing inequality, drug law reform and climate action among them.
However, she is best known outside NZ for a dismissal of a heckle from National MP Todd Muller in 2019 during a parliamentary speech on climate change.
"OK Boomer", she said, producing a viral moment which was seen by millions.
On Friday, she laughed off the sledge, saying she had "never repeated that terminology".
"I hope to continue to do what I have done over the last few years, which is to unify people and to work towards intergenerational necessary change," she said.
Ms Swarbrick also has an Australian partner, Nadine Walker, who has worked in Greens politics on both sides of the Tasman.
Nominations for the leadership - which is also open to grassroots members - close in two weeks.
A vote by the broader membership will confirm the party's next co-leader on March 10.