The last time I saw him, back in February at Waitangi, he cut a lonely figure. Many of the Labour caucus were up there as usual and walking around together in the sun after their marae welcome. Cunliffe, bearded and wearing a faded jacket, was by himself.
He mooched about, pretending interest in the carnival, bought a hot dog and tried to ignore his fellow MPs who were ignoring him.
It was less than three months since he had been sacked from Labour's front bench for failing to whole-heartedly back David Shearer's leadership at the party's annual conference, but even so. It surprised me Labour MPs would treat him like that.
Politicians in my observation are fairly professional about what they do. They all know how politics works and they are usually good-natured to one another behind the scenes.
Cunliffe hadn't done anything unusual at that conference. He had lost the leadership contest with Shearer the previous year and like every ambitious politician before him, he was keeping his options open, biding his time.
When Labour blogs erupted on the eve of the conference with calls for Shearer to be replaced, reporters put Cunliffe on the spot and he was non-committal.
Shearer then delivered a conference speech that satisfied the critics and demoted Cunliffe to prove he was no pussy cat.
Nothing remarkable in any of that. Both of them were following the usual script for these things, so why were the MPs being so rough on him? Either the current Labour caucus are an unusually catty bunch or Cunliffe is worse than he seems.
He is a nice enough man to meet and very smart. Occasionally he says something that makes you wonder about his judgment, such as a comment designed to underline his cleverness in case you missed it.
His is the sort of sparkling intelligence that falls some way short of wisdom. He is a little too sure of himself, not a natural team player. He could be New Zealand's Kevin Rudd.
The wider party has given itself the power to foist him on a caucus that rejected him for Shearer two years ago and reportedly prefers Robertson now. Robertson must be impressive in Parliament, he gets great notices from the press gallery but it isn't apparent on television. He seems keen, loyal and likeable, nothing more.
Cunliffe undeniably has the extra quality needed to lead an election campaign. I doubt that he or his rivals could defeat John Key next year but the winner of this party election could do well enough to survive and ride a turning tide in 2017.
Should we be worried?
I heard a leading Labour MP say the other day that this is a well-governed country. He was referring not just to the present Government but to the previous Government too.
After the upheaval of the 1980s and 1990s, we have settled into a bipartisan consensus of sound public policy, particularly in the monetary and fiscal foundations of a market economy.
The consensus is hard for Labour MPs to maintain because their party outside Parliament does not share it. By and large the activists and unionists have had the sort of education that gives you a jaundiced understanding of economics. It is not until Labour people get a seat in Parliament and read their briefs that the consensus makes sense.
Cunliffe didn't need to read his briefs. Coming from Harvard Business School and the Boston Consulting Group, he already knew everything the Treasury could tell him. He understands the rationale very well and despite the rhetoric he is spinning for the applause of union and party members right now, he believes in it - almost as much as he believes in himself.
He would go where wiser heads fear to tread. He doesn't lack political courage. He claims the credit for putting capital gains tax on to Labour's platform at the last election as finance spokesman under Phil Goff. Some of his monetary ideas are less orthodox.
The public, like his colleagues, might not warm to him but he would bear it. I just worry that his sunny self-belief is a little too large for the country's good.
