Prime Minister John Key will replace US President Barack Obama as chairman of a top-level meeting in Bali this week.
On Friday afternoon, Obama cancelled his trip to the leaders' summit of the Asia-Pacific Economic Co-operation forum on the island because of the American Budget crisis that has resulted in about 800,000 Government workers not being paid.
US Secretary of State John Kerry will represent Obama at the summit, and at the Trans Pacific Partnership meeting on the sidelines.
NZ Trade Minister Tim Groser said it was decided yesterday that Key should chair the meeting of the 12 countries negotiating the TPP agreement.
New Zealand is the official administrator of the trade talks, which began in March 2010.
"Since it is a leaders' meeting, it was felt appropriate that somebody who is a head of government should lead it and the Prime Minister has been chosen," Mr Groser said from Bali.
The leaders are expected to affirm their goal to conclude the TPP by the end of the year.