Dismissing that as nonsense Mr Key, in a line he repeated later in the hour long debate, pointed to National's record on economic management and pointed to the future.
"New Zealanders can see that we're on the cusp of something very special for this country and they want to be part of that."
Mr Cunliffe called National's HomeStart programme which gives homebuyers bigger grants for towards a deposit on new home "pouring petrol" on a fire.
Mr Key counterpunched by saying he had taken a good look at Labour's KiwiBuild scheme to build 100,000 homes saying it would "take years and you build a couple of thousand homes".
On another foreign investment in farmland, another emotive issue for voters both used disputable numbers to make their point.
Mr Cunliffe said over a million hectares of farmland had passed into foreign ownership under National, a number which relies on gross totals.
Mr Key, who by that stage was looking more assured, in turn said the Overseas Investment Office estimated only 1 to 2 per cent of rural land was in foreign ownership - a number that actually represents the amount that has passed into foreign ownership in the last nine years.
Mr Cunliffe argued Labour didn't want New Zealand farms and houses "to be speculative playthings for foreigners we want them to be for kiwi families".
Mr Key countered that New Zealand had to allow some foreign investment.
"If we say no to foreign capital whether its ultimately going into businesses or a little bit going into land then we have to say no to a stronger economy and the things a strong economy will deliver".
After the debate, Prime Minister John Key appeared happy with his performance, but said it was "a bit scrappy" because of the interruptions by Mr Cunliffe.
"[Cunliffe] didn't rattle me but he was talking over me quite a bit. I thought he'd be good, and I thought he'd be aggressive and he was both of those things."
Mr Cunliffe had gone on the attack over Judith Collins and the Dirty Politics book dominated the first part of the debate, but Mr Key said he was expecting it to be raised and it had not bothered him.
Asked to compare Mr Cunliffe's performances with those of Helen Clark and Phil Goff, he said Mr Cunliffe was stronger than Mr Goff, but Helen Clark's grasp on policy details was much stronger after nine years of being Prime Minister.
Mr Cunliffe had faltered over a few questions around Labour's housing policy and capital gains tax details.
By contrast, Mr Cunliffe gave credit to Mr Key for being part of a "positive atmosphere."
He said Mr Hosking had told them in advance they were welcome to parry. "I have no complaints."
He defended himself for failing to have some of the numbers on Labour's affordable housing policy, saying that level of detail could not be worked out unless in Government.
Mr Cunliffe said he had no issues with Mike Hosking's performance as moderator despite Labour's early reservations about an apparently pro-National bias.
"I think he was very professional and fair presenter."
He said he was nervous at the start, but believed the point he had made most clearly was over land and house sales to foreigners. However, he had had to concede Labour may not be able to block the Lochinver bid as originally hoped.
Mr Key went into the debate coming off a poll shock of his own with the 3News Reid Research on Wednesday showing the Dirty Politics fallout had cost National 2.5 points in support leaving it at 45 per cent and probably requiring Winston Peters' NZ First to achieve a majority in Parliament.
But Mr Peters was showing little love to Mr Key yesterday.
In a move that could have been taken as an attempt to wrong foot Mr Key ahead of the debate, Mr Peters claimed trouble plagued Justice Minister Judith Collins of a disloyal power play behind her leader's back.
He told 3News he'd had "back door approaches" from Ms Collins' camp.
He had been approached by a "bagman" for Ms Collins who asked him: "If you can't talk to John Key after the election can you talk to her. That's pretty bold isn't it."
During last night's debate Mr Key said he didn't believe Mr Peters' claims.
Mr Peters said the only headway Mr Key made during the debate was lumping the Green's policies in with Labour's.
"That was not deflected the way it should have been ... But I don't think either side will be happy with the performance."
He said the debate focused too much on the present and not the future economy.
"I thought the critical part of the debate, which is where we are heading in 2015/16/17, was clearly missed.
He said the moderator Mike Hosking gave a "very polished and neutral performance".
Conservative leader Colin Craig said Mr Cunliffe won "by a nose".
"John Key was way too evasive and elusive, he was just trying to brush things off. He was very dismissive of land sales [to foreigners], saying it was not a big deal, but how would he know? We don't even have a register to know what the actual number of land sales are."
He said Mr Cunliffe "did alright".
"He was quoting plenty of facts and figures. I think he'll be happy."
"They were both pretty vague on immigration. They weren't prepared to be clear. We think it should be halved."
United Future leader Peter Dunne said there was no clear winner, and it was unlikely to have swayed any voters either way.
"I don't think you can draw too much from it. They were each shouting each other down."
He said Mr Cunliffe, in his first major test, didn't mess anything up.
"But he didn't shut up, and that distracted from the whole spectacle. You can be assertive in a debate without being obnoxious, and Cunliffe strayed close to breaching that."
