Prime Minister John Key insists he is not protecting Education Minister Hekia Parata and denies she has become a minister in name only.
Ms Parata survived a Cabinet reshuffle on Tuesday after a difficult year in the job, but Economic Development Minister Stephen Joyce has been put in charge of fixing the error-ridden school pay system, Novapay.
Mr Key told Radio New Zealand's Morning Report programme that education is always an area of controversy where many new ideas are shouted down, and Ms Parata needs more time to make a full assessment of the sector.
"I think she's made one or two mistakes, but I also think she's done a lot of things right that she hasn't been given credit for.
"Any minister fronting the necessary changes in Christchurch would be criticised."
A series of problems in education last year included controversy over the Government's proposal to close or merge 39 schools in the Christchurch area, the High Court's overturning of a decision to close a special needs girls' school in Nelson and failures in Novopay.
Mr Key says Ms Parata is talented and cares deeply about turning around under-achievement.
Novopay fix will take time, says Joyce
Mr Joyce will be the third minister to try to fix Novopay, after Ms Parata and Associate Education Minister Craig Foss who is being stood down from that portfolio.
Mr Key says he is hoping to see rapid improvements in the teachers' pay system once Mr Joyce has made a frank assessment of the situation.
The $30 million system developed by Australian company Talent2 has been plagued with errors since it was introduced in August 2012, with underpayments, overpayments or no payments at all to some staff.
The Labour Party says Novopay should be handled by the Education Minister not the Prime Minister's fix-it minister.
However Mr Joyce says he is one of a number of Cabinet members with a number of roles and he's happy to help out.
"I think at different times the Prime Minister asks different people to do different things", he said.
"This time it's my turn and I'm happy to get on and see what we can sort out."
Mr Joyce says it will take some time to get the system working properly. He says Novopay is a complex system and he will talk to all those involved to get a clear understanding of how it should work.
The Post Primary Teachers Association (PPTA) said Mr Joyce will need luck in solving the debacle. President Robin Duff said the problem needs a lot of work, and needs it very quickly.