John Key gave the wrong answer when asked on Friday whether he would have happily sent his children to a charter school.
His instant and firm "yes" when put on the spot was the natural reflex of a politician conscious that any hesitancy or obfuscation on his part would have seriously undermined the Act-instigated policy before a single such school had even got off the drawing board.
But the Prime Minister should have emphasised that charter schools will not be filling their rolls with the offspring of well-heeled residents of Parnell. He should have stressed "partnership schools" - to give them their new official and sanitised title - are being tested as an alternative in areas of significant socio-economic disadvantage, such as parts of south Auckland, where children struggle to learn and the present state school system, for all its strengths, is failing to deliver much in terms of acceptable results.
It is only by framing the political debate on those terms that National and Act will have any hope of turning around majority public opinion that remains convinced the policy - for which there is no electoral mandate - is the thin end of a big wedge that will increasingly farm out compulsory education to private interests to run for profit.
Friday's announcement laying out the terms and conditions for setting up and running partnership schools succeeded only in making the selling job even more difficult.