Labour stalwart Brian Edwards says the party's move to the political centre, which was further hinted at in new leader David Shearer's speech last week, is driving him away from the party and into the arms of the Greens.
Writing on his blogsite, Dr Edwards, who was former Labour Prime Minister Helen Clark's media trainer, biographer and friend, said Labour's philosophical and moral values "are now so ill-defined as to be beyond definition".
"I find myself wondering whether I want to be bothered with the Labour Party any more. Increasingly, it seems to me, the Greens reflect the philosophical and moral values to which I subscribe more accurately than the Labour Party."
Dr Edwards said Rogernomics and the influence of former British Labour Prime Minister Tony Blair's "third way" on Ms Clark's Government had moved Labour from its socialist roots.
Mr Shearer appeared to be moving Labour further into the middle ground occupied by National and the distinctions between the two major parties were less clear, "both promising to deliver 'a brighter future' and the Labour leader ditching policies specifically directed at putting more money into the pockets of the poor".
"What Labour politics now seem to be about is finding 'sellable' policies and a 'sellable' leader in order to regain power."