But the Labour leader threatens to be distracted by internal ill-discipline and criticisms over his judgment, including the holiday itself and a meeting last week with a prominent New Zealander given name suppression on charges of performing an indecent act.
Mr Cunliffe confirmed to the Herald last night that he had arranged for the person - whose case has been the topic of media coverage - to meet a Labour candidate but said he had no idea about the controversial background until yesterday.
"If I had known of the suggestion, no such meeting would have taken place."
Mr Cunliffe spent three days last week on holiday in Queenstown then two days campaigning in other parts of the country.
One of his MPs broke ranks to condemn the holiday anonymously in the Sunday Star Times.
The holiday issue was also raised when the Labour front bench met in Auckland yesterday - a long-planned meeting, Mr Cunliffe said - "but it wasn't a key feature of discussion".
However, he was clearly upset by the remarks. "I think it is very sad whoever has talked to a newspaper without the integrity to put their name to it, and if anybody has any concerns, my clear expectation is they will come to me privately rather than talk to the media," Mr Cunliffe said.
"We are a collective and we owe it to the party and to New Zealanders to operate collectively, to bring Kiwis the opportunity that they deserve for a better start, more opportunities for them and their families."
Mr Cunliffe said the claim he had a week off was wrong anyway.
"The facts are I had two days in bed with flu. I had three days at a skifield with my children and wife.
"I was encouraged to do so to recharge the batteries before the campaign and crucial debates and acknowledging that my family won't be seeing much of me for the next nine weeks.
"That was a decision that was made in good faith at the time. It has left me with batteries recharged and ready to run. I am very, very keen to run."
Mr Cunliffe said no colleague had suggested to him he should step down and he had no plans to do so.
Mr Key emerged in public yesterday, defending his own 10-day break in his Hawaii holiday home and pointing to Labour's woes.
He said he worked 19-hour days and election campaigns required a different type of intensity.
He said the outburst by the Labour MP in the Sunday paper delivered a pretty simple message.
"If you can't manage yourself, you can't manage the country."
Commenting on the polls, which consistently show Labour falling to around the mid-20s, Mr Key said Labour was not the risk to National; the combination of Labour, Greens, Internet Mana and potentially New Zealand First was.
He believed it would still be a close election.
The weekend's Herald-DigiPoll results showed Labour falling by four points to 26.5 per cent, the lowest the party has polled in any DigiPoll survey since 1999.
The weekend poll has National on 54.9 per cent (up 4.5 points since June) and the Greens on 9.9 (down 0.8).
The poll of 750 decided voters was taken between July 10 and 17. Undecided voters were 11.5 per cent. The poll has a margin of error of 3.6 per cent.
