John Key said he never saw himself as a career politician, and that it was a good time for him to go.
New Zealand's Prime Minister John Key unexpectedly announced his resignation on Monday after eight years in office.
At an emotional press conference, Key said he would not seek a fourth term and cited "family reasons" for his surprise resignation.
"Despite the amazing career I have had in politics, I have never seen myself as a career politician," Key said.
"Over the years I have observed many leaders who, in a similar position, fail to take this step. I can understand why. It is a hard job to leave… But, for me and the National Party, this is a good time to go."
Following the news, Bill English, who is both deputy prime minister and finance minister in Key's cabinet, said he is deciding whether to stand for the leadership of the ruling centre-right National Party.
Key's main rival, Labour leader Andrew Little, paid tribute on Twitter to Key's decision.
John Key has served New Zealand generously and with dedication. I wish him and his family the best for the future.— Andrew Little (@AndrewLittleMP) December 5, 2016
Australian Prime Minister Malcolm Turnbull tweeted praise for Key.
John Key has been an extraordinary & inspiring world leader, role model and great friend. His resignation is a great loss for NZ & the world— Malcolm Turnbull (@TurnbullMalcolm) December 5, 2016
Former Prime Minister and Labour leader Helen Clark sent her good wishes.
Wishing @johnkeypm & his family all the best for the future. He has advocated tirelessly for NZ internationally these past 8 years.— Helen Clark (@HelenClarkNZ) December 5, 2016
New Zealand's Green Party also paid tribute to Key and said in a statement, "No matter your political allegiance, you have to respect someone who chooses to make the personal sacrifices required to be our country's Prime Minister."
Key's resignation was criticised, however, by the leader of the New Zealand First Party, Winston Peters, who said Key's decision came as no surprise.
"The fact is that the economy is not in the healthy state that the Prime Minister has for so long claimed, and there are other issues which have caused this decision as well," Peters said.
"Contrary to certain perceptions the Prime Minister and his Finance Minister are unable to muddy the waters anymore. The New Zealand public should have been informed of this a long time ago."