Green Party leader Natalie Bennett is to stand down in the summer after four years at the helm of the party.
Bennett told The Guardian that she would not stand for re-election when her second two-year term in office expires at the end of August.
"There have been times when I got things right, and times when I got things wrong, but that's because I'm not a smooth, spin-trained, lifelong politician," she told the paper.
"It's both my strength and my weakness that I answer the question."
The Australian former journalist came to prominence during the televised leaders' debates in last year's general election.
But while the party membership rose from 13,000 to 60,000 under her leadership, it failed to make the hoped electoral breakthrough - just holding its single parliamentary seat - Caroline Lucas at Brighton Pavilion.
Bennett famously had to apologise to members following an excruciating radio interview in which she blamed "brain fade" for her inability to explain a series of party policies.
In a statement, Bennett said that she intended to remain "fully engaged" in Green Party politics.
"I have been proud to lead a party through a period of phenomenal expansion and increased impact. With the support of our passionate members and supporters we have been able to achieve much in a relatively short period," she said.
"There's greatly increased public understanding that when you want the honest, caring, committed view - one that isn't guided by the views of the latest focus group or fear of a tabloid backlash but by fundamental principles and values - you should come to the Green Party."
Nominations for Bennett's successor will open on June 1 and close on June 30.
A one-month balloting period will begin on July 24 with the result to be announced at the party's autumn conference in September.