The TPP has two years to be ratified but will not come into force unless the US and Japan ratify it.
US Trade Representative Mike Froman told the TPP press conference he was "confident" members of Congress would see the benefits of the deal for the US economy and their constituents "and we'll have the necessary bipartisan support for it to be approved".
Australian Trade Minister Andrew Robb suggested the TPP was the beginning of something much bigger.
He said the other giant trade deal, the RCEP, which includes China and India (as well as New Zealand and Australia) could be concluded this year and eventually be merged with the Trans Pacific Partnership to form the basis of an even bigger trade treaty across the Asia Pacific.
Mr Froman sought to address concerns about the investor-state dispute procedures in which investors and a government in dispute can enter binding arbitration.
He said the 12 countries had shared a number of concerns about the way these procedures had been used "and that's why this agreement goes further than any agreement before". That included closing loopholes they had seen in other agreements "to ensure that government can regulate in the public interest".
Prime Minister John Key said it was an important day for New Zealand signing a deal that opened up huge market access. He described the demonstrators as "rent-a-protest" and said the same people would turn up to protests against the sale of SOE shares, against ministers and one was even holding up a sign against 1080.
New Zealand Trade Minister Todd McClay, who has been in the job for less than two months, chaired a ministerial meeting before the signing, and ran proceedings at the signing.
Mr McClay confirmed to the Herald that the bill containing enabling legislation for the TPP, amending various existing acts, would be presented as a single omnibus bill through all stages.
That will force Labour to vote against the bill at its final reading rather than cherry picking.
Labour leader Andrew Little has said Labour would support the part of the bill that cuts New Zealand tariffs on imports - a reciprocal move for the cutting of tariffs of other TPP parties on goods exported by New Zealand.
He did not attend protest rallies.
What next
• 12 TPP countries have two years to ratify the TPP through their respective domestic processes.
• TPP enters into force under a formula which means the US and Japan must both have ratified it for it to take effect.
• Trade Minister Todd McClay tables the national interest analysis (NIA) in Parliament next Tuesday, although it has been released.
• Parliament's foreign affairs and defence committee considers NIA and hears submissions on it.
• Assuming the NIA is accepted, the Government draws up legislation required to enact some part of the TPP.
• TPP legislation is introduced to Parliament and referred to the foreign affairs and defence committee for consideration.
• Amendments to legislation will take effect only if the TPP is ratified.
