Primary school teachers are considering opposing the Government's $360 million plan for creating new roles for top teachers and principals.
The policy involves 6000 educators being paid more to work across groups of schools to improve education.
New Zealand Educational Institute national secretary Paul Goulter says opposing the policy is still a distinct possibility.
Mr Goulter says the union is yet to see any evidence that creating the new roles will improve student achievement.
He told Radio New Zealand's Morning Report programme it wants to see evidence that spending money that way will work, because it is not a matter of one size fits all.
"I know our members were very cynical about what the Government's trying to do here because they cannot see a line here between what the Government's proposing and how it will lift student success across the country," he says.
"We've consistently called for evidence to do with that. No evidence has been provided."
The union's executive is meeting on Tuesday night to discuss the policy.
On Monday, the Principals Federation released a list of conditions it requires if it is to continue to be involved with the policy.