Mr Cunliffe suggested he had been handicapped by having been Labour leader for only a year.
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Having lost a leadership contest straight after Labour's loss in the 2011 election, he was elected in September last year after David Shearer stepped down.
It was also difficult for an Opposition party being up against the resources of state.
But he was having fun on the campaign and many dedicated Labour supporters were campaigning hard.
Speaking about the shape of a Labour-led Government, Mr Cunliffe said it was he would like to put a "solid coalition" potentially across Labour, the Greens and New Zealand First.
It was clear that the largest coalition governed, not the largest party.
"So there is every possibility of putting together a governing coalition across Labour the Greens and potentially New Zealand First."
Mr Cunliffe has ruled out having Internet-Mana MPs in ministerial positions but is open to a doing a confidence and supply agreement with the alliance.
The decision was "a really a matter about New Zealanders' "comfort levels" with a brand new party that had no track record and was bankrolled by Kim Dotcom.
"I would rather work with parties that have had years and years of experience, like the Greens and New Zealand First."
He did not rule out following the practice of Prime Minister John Key is having parties in Government whose vote Labour might not actually need.
National has done that with the Maori Party for its two terms in Government.
"I thought that was a constructive thing that the Prime Minister did at that occasion," Mr Cunliffe said.
He would not comment on the desire of the Green co-leaders, Metiria Turei and Russel Norman, to become co-deputy Prime Ministers.
But he reiterated that the finance portfolio would definitely stay with Labour.
THE VIDEO SERIES SO FAR
Thursday - Hone Harawira and Laila Harre, Internet-Mana
Friday - Colin Craig, Conservatives
Saturday - Jamie Whyte, Act
Monday - Peter Dunne, United Future
Tuesday - Te Ururoa Flavell, Maori Party
Wednesday - Russel Norman and Metiria Turei, Greens
Tomorrow - John Key, National