Ms Beard said it was difficult to understand why Labour supported the China free trade agreement but not the TPP, "when they are similar in all major respects". She described Labour's position on the TPP as a step backwards for the country's export competitiveness.
Labour Party leader Andrew Little confirmed earlier this week that his party would oppose the 12-nation trade deal because it would undermine New Zealand's sovereignty.
The party's Maori caucus was also concerned that the trade deal could affect the Government's Treaty of Waitangi obligations.
Maori Development spokesman Kelvin Davis today said that Maori opposition to the historic trade deal was growing by the day.
He said the Iwi Leaders Forum had come out against the deal after meeting with Trade Minister Todd McClay.
"Maori leaders, academics, clinicians, the CTU Runanga and the Maori Women's Welfare League are firmly against the deal. Ngati Whatua, Ngati Paoa, Ngati Te Ata and Ngati Whanaunga each confirmed they would not perform the powhiri for the signing of the TPPA."
Labour's position on the TPP has not been unanimously backed by its caucus.
Foreign affairs spokesman David Shearer is facing censure for speaking in support of the TPP in an interview with the Herald earlier this week.
Labour's trade spokesman Phil Goff has also publicly backed the TPP, but Mr Little said he had given permission to Mr Goff to take his own position because of his long-standing connection to the agreement which he initiated while he was Trade Minister.