Grant Robertson says he will never run for the Labour leadership again after narrowly missing out to Andrew Little this afternoon.
Despite leading in both party votes and caucus votes, Mr Robertson didn't have the overwhelming support of the unions that Mr Little did.
Mr Robertson offered his congratulations to Mr Little and said he remained committed to the Labour party, but never in a leadership sense.
"I want to make clear that having put myself forward for the leadership on two occasions now that I will not do so again," Mr Robertson said.
"I will do whatever is asked of me to see that [Labour] government elected".
In the third and final round of results, with only two candidates still standing, Mr Little scraped through with 50.52% of the vote over Mr Robertson's 49.48%.
Nanaia Mahuta was eliminated in the first round and David Parker bowed out in the second.
Mr Little's success is largely down to his support from New Zealand's largest trade union, of which he used to be National Secretary.
Bill Newson, who succeeded Mr Little as Engineering, Printing, Manufacturing Union National Secretary, congratulated his former colleague, revealing that they had "unanimously endorsed" Mr Little.
Green Party co-leader Dr Russel Norman also welcomed the news, commending Mr Little for running an "open and democratic leadership contest".
"We look forward to continuing to build a constructive working relationship with Labour and to help make New Zealand a better, fairer place to live," Dr Norman said.
Mr Little says he hopes that all three of his fellow candidates will play senior roles in the Labour Party going forward.