For them it is payback time. Cunliffe's championing at last year's conference of the push for more democracy within the party ultimately paid off for him, cementing his status as the wider party's preferred choice as leader.
But everything comes at a price.
Cunliffe is the left's man. They have given him a power base outside the caucus. They have got him where they want him. He is now expected to start backing up the rhetoric, which only stretches so far for so long, with some real substance.
And judging from conference papers alone, that means heading in one direction - leftwards.
The question non-partisan observers will be asking is whether the content as much as the tone of today's speech, plus a separate as yet unspecified policy announcement timed for tomorrow, will be enough to obscure tensions over the party's direction - the unfinished business from last year's conference.
This year's gathering is not going to be a repeat of that shambolic and confrontational affair. But it is most definitely a sequel, a kind of Revenge of the Nerds II.
Marching leftwards is neither in Cunliffe's best interests nor Labour's, as a mainstream party.
However, for sections of the wider membership, Cunliffe's victory in the leadership race was part of a power struggle for Labour's soul.
Those elements seem more fixated with winning internal battles in the political sandpit rather than confronting National in the bear pit.
They would seem to prefer engaging in a pointless and unrewarding war with the Greens for the relatively few votes on the far left.
All this has prompted some dark mutterings in some quarters about the lunatics having finally taken over the asylum.
Cunliffe is obliged to go along for the ride, at least for now.
So far he has managed to remain all things to all men and women by speaking out of both sides of his mouth. Again, however, he can only get away with that for so long.
National cannot believe its luck. It is puzzled by Cunliffe's invisibility in recent weeks as well as a seeming lack of urgency, given his immediate declaration of war on the old enemy on being elected leader back in September.
Indeed, a year out from a general election and less than a month out from a must-win by-election in Christchurch East you might think Labour would want to use the conference as a giant billboard conveying if not the detail of a fresh blueprint for achieving a more prosperous society for all, then at least providing a taster.
You could be excused thinking this might also be an opportunity for the caucus spokesmen and women in key portfolios to give some indication of their thinking even though they may not have been in those roles for very long.
Instead the conference will devote several hours to wrangling over the wording of a "policy platform" document setting out Labour's values, vision and priorities which has already been months in the drafting.
The platform is supposed to answer that perennial question: what does Labour stand for.
You can safely bet that 99.9 per cent of all voters will never set eyes upon it, let alone read it.
This is the kind of navel-gazing exercise a party undertakes and completes in the year after an election - not a year out from the next one.
It all reinforces the impression of a party focused inwards rather than outwards.
That is underlined by the series of policy remits which deal with such pressing matters as compulsory Maori language classes in schools, apologising to Maori over the foreshore and seabed farrago, state funding of political parties (a hardy annual) and entrenching the Bill of Rights (whatever difference that would make).
Many of the items amount to wish-list policies produced by the party's sector groups. The words "out of touch" spring to mind.
Even on a matter of moment - state asset sales - Labour seems to be living in the past. One proposal up for debate at yesterday's workshops would have had a Labour government reviewing the state-owned enterprises model so that it was no longer "pro-capitalist" and enabled "workers' participation, control and management of industry".
The "policy proposal" would have also required Labour to "re-nationalise" every state asset privatised by the current National Government, with compensation being paid only to shareholders with "proven need".
That is a blunt retort to Bill English's jibe that if Labour opposes asset sales so much, why doesn't the party commit itself to borrowing the money to buy them back.
Exactly where the line would have drawn on compensation is not clear. But there would be some mighty unhappy investors in Mighty River Power if told they were not going to get their money back. That would amount to theft - and would have seriously dented New Zealand's credibility as a haven for foreign investment, as well as sending all the wrong messages about saving.
The proposal was voted down by delegates. The question is how it managed to make it onto the conference agenda - and why something better was not put up in its place. Sometimes political parties need protecting from themselves.
Labour's membership may feel liberated by recent changes in the party's rules. But more influence brings the need to act more responsibly. At some point, however, Cunliffe is going to have to lurch back to the right. It won't happen today. But it will happen. Watch for some real fireworks within Labour when it does.
