The $2.7 billion boost to the economy amounted to a 0.9 per cent lift to GDP in 15 years' time. The New Zealand economy was projected to rise by 47 per cent over this period, Labour said.
The Green Party and New Zealand First also expressed their opposition to the agreement in their minority reports.
Today, Mr McClay said he was not surprised by Labour's stance, although it "flies in the face" of the party's history of championing free trade agreements.
"TPP meets every one of the bottom lines set by the Labour Party. New Zealand businesses will rightly be questioning how Labour, by not supporting one of the most comprehensive and valuable trade deals ever negotiated for New Zealand, can claim to support exporters to grow and create new jobs."
Labour leader Andrew Little said the trade minister was right to point out Labour's long history of supporting free trade agreements.
"It goes back to the first Labour Government, and our support for free trade hasn't changed. But what we won't support is the erosion of New Zealanders' democratic rights and to have a sovereign government. That's what the National Government is selling out."
In January, Mr Little gave senior MP Phil Goff special dispensation to vote for the TPP, because during Mr Goff's time as trade minister he started the negotiations for the agreement's predecessor.
Fellow Labour MP David Shearer had told the Herald he personally supported the TPP, but later said he would be voting along party lines.