John Key has talked up Helen Clark in his speech to the United Nations General Assembly, saying only she can keep it relevant - a major swipe at the other candidates and countries.
Mr Key bluntly told the UN, known for its inaction, that "she gets things done".
"This is not the time for a business as usual appointment for Secretary-General. We need someone who is up to the job," Mr Key said.
"The next Secretary-General must have the courage, experience and skills necessary to lead this Organisation, to keep it relevant and responsive."
Mr Key's decision to use Ms Clark in his speech elevates the New Zealand campaign for her to be Secretary-General to another level.
His comments are also a swipe at current Secretary-General Ban Ki-moon.
"I've worked across the political divide from Helen Clark for years and I know her to be a natural leader," Mr Key said.
"She rallies people together to find the common ground, even when the issues are difficult and the differences vast.
"She gets things done. We think it's time for a Secretary-General like Helen Clark."
Mr Key says the United Nations Security Council has failed Syria.
"We have also been deeply troubled to see the Council, the pre-eminent body for international peace and security, fail to live up to its responsibilities on the most serious crisis of our time. Syria.
"Here the Council has fallen short," he said.
"The internal politics within the Council and the sheer complexity of the Syria crisis have obstructed a unified Council response.
"But we believe that no matter how difficult and sensitive the issues, the Council cannot watch the situation go from bad to worse for the Syrian people.
"The Security Council was established to address crises like that which we see in Syria.
"That is why New Zealand is using our Presidency of the Council to convene a leaders' level meeting tomorrow on Syria.
"A meeting by itself won't stop the conflict. But after more than five years of brutal fighting, and horrific humanitarian suffering, we do not think it is credible for Leaders to come to New York and not address the stark realities driving the conflict."
"We hope tomorrow's meeting will provide an opportunity for Council Leaders to take stock of developments, examine the fundamental issues at the heart of the conflict, and discuss how we can move towards a sustainable political solution.
"We also hope the meeting will be a chance for the Council to put its weight behind the ceasefire agreement reached between the United States and Russia.
"That agreement is the best chance we have had in some time to stop the fighting, get aid to those who need it, and get back on track for a political resolution to the crisis."
Mr Key also took the fight to trade protectionism of the kind put forward by Donald Trump, or Brexit.
"Borders are closing to people and products, to investment, to ideas. Many states are turning inwards."
"The politics of fear and extremism are gaining ground. Too many states are flouting the rules."
"We must guard against creeping protectionism, and be willing to make the case for more economic engagement clearly.
"We cannot turn inwards," he said.
"We can't allow fear, or narrow domestic interests turn us away from an open global trading system, which has lifted millions out of poverty."
John Key made special mention of the danger of North Korea and its Nuclear weapons.
"Another critical issue on which New Zealand supports unified Council action, is the Democratic People's Republic of Korea.
"New Zealand believes that a strong international response is required to the DPRK nuclear test on the 9th of September, and its recent missile tests.
"The regime's efforts to advance its nuclear and missile programmes; its callous disregard for the North Korean people - as demonstrated by the dire human rights situation in the country; and its leader's unpredictably ruthless rule have made it one of our most pressing international security threats.
"Its provocative actions show blatant disregard for Security Council resolutions and pose a grave threat to the international law.
"They have raised tensions on the Korean peninsula to a point where the risk of conflict is dangerously high. We cannot afford further escalation.
"So New Zealand welcomes recent steps by the US and China to begin negotiating a new Security Council Resolution, following the DPRK's recent nuclear test.
"We hope that this will send a clear signal to the North Korean leadership that continued provocative and dangerous actions are unacceptable; and that a return to the negotiating table represents the only sensible way forward."
"We need it to find common ground that overcomes vested national interests, and agree to new international trade commitments that benefit all countries.
"In the Asia Pacific region, closer economic integration through trade agreements like the Trans Pacific Partnership and Regional Comprehensive Economic Partnership will also bring us closer together.
"Agreements like these will make our region and people better off by setting the conditions for more open and transparent trade."