National struggles on current issues 

National leader John Key has been riding high in the polls but this week he's taken a tumble.

Key struggled to explain himself on Wednesday when questioned on when Treaty of Waitangi claims are expected to be wound up.

National's 2005 policy says that the party will complete historical Treaty grievance settlements by 2010.

In 2007 National set another settlements date for 2014. On Wednesday, Key struggled to elaborate on the current deadline.

National is also under pressure to spell out its position on the partial sale of Auckland International Airport.

The government has amended the law in response to the Canadian Pension Plan's bid for a 40% stake in the airport.

Under the change, ministers will be able to block the sale of assets to a foreign company if it runs counter to the need to maintain New Zealand control of what it calls "strategically important infrastructure on sensitive land."

National initially struggled to communicate its position but have now spoken out on the government decision.

Key says he does not support the amendment and that it is ambiguous in the way it's drafted.