He was right. He hated seeing his prediction come true.
For telling this truth he ended up walking, alone, from a Labour caucus he had done as much as anyone to elect, leading much of the membership first to challenge their Government, and then out of the party.
But for that split, MMP would not have got off the ground. But pre-MMP he battled in Parliament alone for three years and then for three more with only one MP beside him, the formidable Sandra Lee.
Jim left Labour when it decided to sell the BNZ. He campaigned for a Kiwi bank. Academics, MPs, the Reserve Bank and Treasury all predicted it would fail. Today, Kiwibank is profitable and has hundreds of thousands of happy customers.
In Government he started a Ministry of Economic Development and NZ Trade & Enterprise. He called for a reformed Reserve Bank Act and changes to overseas ownership rules. His critics shrieked and jeered he would turn the economy into a "Polish shipyard" and "North Korea".
Now a Labour-led Government is implementing those changes and the National Party was persuaded enough about state intervention in the economy to create the gigantic Ministry of Business, Innovation and Employment.
He didn't win every battle. Inequality and poverty were the dominant themes of the election, which underlines Jim never coaxed enough support to fix them. But he was right. If working people today had the same share of national income they had in 1990 we would each be $10,000 a year better off. Less poverty, less inequality.
Jim's socialism was Catholic: our rights stem from our common humanity, and our right to a decent life is balanced by our shared responsibility to each other. He applied to these values three crucial political strategies.
First, inspired by Pope Paul, Martin Luther King and later by Nelson Mandela, he sought to bring about change through sheer force of will. His capacity for work exhausted, often exasperated, colleagues, staff, loved ones. It took too much of him from some of those closest to him. Many of those who fell out with Jim simply under-estimated his relentlessness in fighting as hard as he could.
Second, he would walk away from any institution, party, or movement if it placed itself against the interests of the people. Sounds simple, but hardly anyone does it because the costs are very high.
Chatting over his career around the time he retired we asked him if he still thought the decision to leave Labour had been correct. At the time, 1989, he believed (as did we) that Labour was not reformable. He and we turned out to be wrong about that. Yet he never changed his mind and to his dying day he insisted he could not have asked his constituents to vote Labour in 1990.
But there was a third character trait that was perhaps the most principled of all: If he could achieve more for his constituents by being cooperative and compromising, then he would work with whomever he had to even if it destroyed entire political movements.
His decision to reach out to Helen Clark (and her decision to accept), after nearly a decade of civil war on the left, changed history.
At the time it was bitterly debated internally. We drove with him from the Taranaki-King Country byelection to Auckland one night as he rang around his senior Alliance colleagues to get their support for collaboration with Labour. Some warned that the whole point of the Alliance had been to replace Labour as the dominant party of the centre left and it might not survive a coalition.
"So what?" he replied, astonishingly. "No party has a right to exist. If we can't do what's best for the people we represent then we shouldn't exist."
Five years later he would make the same point when the Alliance imploded. It had exhausted its purpose when it became an obstacle to re-electing a good government.
So why didn't he rejoin Labour later, after he had been in coalition with Helen Clark's Labour for nine successful years? By then too much water had flowed under the bridge for him personally.
The media never really warmed to his refusal to play the press gallery game, to charm and schmooze. His way of winning arguments was to talk and talk and talk, which made for interminable press conferences and frazzled press secretaries.
The greatest figures in public life are tough and courageous in the service of their fellow citizens, even at the potential cost of their personal careers. Jim's legacy is a model for anyone in public life.
In his defence of the most vulnerable, and his sense that everyday working people need a champion to have a chance, Jim was the toughest of his generation.
* John and Josie Pagani were introduced by Jim Anderton and served for a combined total of more than 30 years as his press secretaries and senior advisers. Jim Anderton was godfather of their son, Carlo.