This table I produced the other day shows core Crown expenditure is not a major issue. The real issue is welfare spending along with unreal increases in Health and also in Heritage and Culture spending until 2016. Core government services actually decrease over this period. Ipso facto, government ministries are not a "real" issue.
The biggest monkey in welfare is WFF, but this remains unchanged. The other large cost - financing - includes things such as interest free student loans, and increases from $2billion to 4billion in nine years, but if you tried to solve that you'd be in opposition. So you do very little about it.
All in all, as Steven Joyce said the other day, you can make some changes on the margins.
But that's just National being like Labour, but doing it slightly better.