Prime Minister John Key has resigned.
He made the announcement at a news conference at Parliament on Monday afternoon.
"Being leader of both the party and the country has been an incredible experience. "
He spent much of his announcement re-counting his and his Government's achievements over the past eight years.
He cited pressure on his family as one of the reasons for stepping down.
"Throughout these years I've given everything to this job, the job that I cherish and for the country I love.
"All of this has come as quite some sacrifice for the people who are dearest to me - my family. For my wife Bronagh, there have been many nights where she was alone, many occasions that were important to her that I simply couldn't attend."
As for his future, Mr Key says for him "and the National Party, this is a good time to go".
"I don't have any plans. I'm a commercial guy - I'm not looking for any postings overseas."
"It'll be a slightly quieter life."
It could involve being on a number of company boards, or international speaking engagements.
He says he'd back whoever is the rest of the caucus picks as his replacement.
"Whoever the caucus selects will have my unwavering support. If Bill English puts his name forward, I will vote for him."
Mr Key has held the Helensville electorate since 2002, and was elected unopposed as the party's leader in 2006. He has consistently been New Zealand's most preferred Prime Minister during his reign.