The Government is hosting one of the United States' most influential senators, Max Baucus, for a visit and Prime Minister John Key is expected to discuss the Trans-Pacific Partnership agreement with him.

Mr Baucus is chairman of the US Senate finance committee, and Trade Minister Tim Groser says he is influential on trade policy and especially trade agreements.

He is a Democratic senator of 34 years' standing and has long supported a free-trade agreement with New Zealand.

New Zealand's Ambassador to Washington, Mike Moore - a former head of the World Trade Organisation who is back home at present - said yesterday that it was in the United States' interests to complete the TPP agreement being negotiated among 11 countries - New Zealand, Singapore, Brunei, Chile, the United States, Australia, Peru, Vietnam, Malaysia, Canada and Mexico.


"They know they have to set the standard in the Asia-Pacific," he said on TVNZ's Q+A show.

The US also knew that Japan, Korea, Taiwan, the Southeast Asian countries, Australia and New Zealand were all doing more business with China than the United States, and the US had to have a stronger economic presence in the region.

Meanwhile, the Green Parties of New Zealand, Australia and Canada are joining forces to campaign against the Trans-Pacific Partnership.

They issued a joint statement yesterday after Metiria Turei, co-leader of the NZ Greens, held a press conference in Canada with her counterpart from there.

Among the Greens' concerns is the prospect of the heavily protected Canadian dairy industry being de-regulated, removing safeguards which they say aim to preserve farmers' livelihoods.

They also claim that free internet could be in jeopardy, that intellectual property provisions could inflate the costs of books, that parallel importing could be banned and that state drug-buying agencies such as Pharmac could be threatened by the agreement.

They also called for greater transparency of the process.