"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 towards a deposit on a new home, "pouring petrol" on a fire.
Mr Key counter-punched 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 foreign investment in farmland, 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, said the Overseas Investment Office estimated only 1-2 per cent of rural land was in foreign ownership - a number that actually represents the amount that has passed into foreign ownership in the past nine years.
Mr Cunliffe argued Labour did not 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 it's 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."
Mr Key went into last night's 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.
Mr Peters showed 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 accused Justice Minister Judith Collins of a disloyal power play behind her leader's back.