National says the number of social houses has fallen while it's been in government, but it's promising to change that if re-elected.
Labour says it believes that over two terms, it can end homelessness in New Zealand.
National's Social Housing spokesperson Amy Adams told TV3's The Nation social housing has dropped by 1200 since 2009, in part because of the Canterbury earthquakes.
But she said the problem was being addressed.
"We are increasing the stock 2000 net every year, double what Labour is promising, but in the same time we're also increasing the quality of the stock, we're improving the tenancy services surrounding it."
Labour's housing spokesperson Phil Twyford said his party would increase social housing stock by a minimum of 1000 per year.
He said Labour had bolder ambitions than National and was committed to a New Zealand strategy to end homelessness.
Mr Twyford said the Salvation Army estimates homelessness at 41,000, but Ms Adams said the government's survey puts the figure at 4200.