Richard Di Natale has resigned as leader of the Greens and will leave federal parliament.
Senator Di Natale cited family reasons as he made the announcement to Greens colleagues on Monday, immediately spilling his position as leader and those of co-deputies Adam Bandt and Larissa Waters.
"My boys are nine and 11 years old and they have only ever known their dad as a busy, tired and sometimes grumpy politician," he said.
"As they grow up quickly to become young men, I want to spend more time by their side than a relentless political schedule allows."
Senator Di Natale was first elected in 2010 and became federal parliamentary leader in May 2015, following the resignation of Christine Milne.
In accordance with protocol, the 10-member Greens party room will vote for a new leadership team on Tuesday.
It is expected the role could go to either Senator Waters or Mr Bandt.
The 49-year-old backed the "intelligence, compassion and courage" of his parliamentary colleagues heading into the ballot.
"The success of our party and cause has never and will never depend upon one person," Senator Di Natale said.
"Our party will succeed because we are part of a much broader community movement, a movement that is growing stronger each day."
Senator Di Natale said there were many things he was proud of, singling out the 2010 carbon price negotiation, the royal commissions into the banking and disability sectors and the legalisation of same-sex marriage.
Australian Associated Press