Prime Minister John Key has called Labour's housing policy unrealistic.
Labour wants to put 100,000 New Zealand families into new, affordable homes within the next 10 years.
It believes it can build the houses for just over $300,000 each and sell them with a small margin.
But Mr Key says Labour is in fantasy land.
He says while it may be possible to build a house for that price, it would not be what first-home buyers would be expecting as it would most likely have little land and be a long way from any city centre.
The Prime Minister says it is also likely that the policy will cost a lot more than the $1.5 billion that Labour is estimating