Principals say they're puzzled about why the Government has invited 120 of them to Wellington for a briefing on its Schools Plus policy.
Prime Minister Helen Clark last week announced further details of the plan which will keep students at school or in training until they're aged 18.
National's education spokesperson Anne Tolley has accused the Government of a shameful waste of taxpayers' money on what she says is electioneering.
The Principals Council says paying for so many principals to come to Wellington is a rare thing and has only happened once before.
Acting chair Julia Davidson says that after the announcement on Friday, it's hard to see what else the Government has to say about Schools Plus at this stage.
A Ministry of Education spokesperson says it decided to hold the briefing because Schools Plus is a major policy. Some 120 were invited - the ministry says only 50 will attend on Wednesday.