Sunday's announcement has provided breathing space for those Budget items still under wraps which Key and Bill English will want to highlight on Thursday without unwanted distractions. That includes measures to tackle "material deprivation" - bureaucrat-talk for "child poverty".
National's fumbles have allowed Labour to claim minor victories in the battle over which major party can claim the right credentials for running the economy.
Knowing the Government holds all the cards on Budget day, Labour leader Andrew Little and his finance spokesman, Grant Robertson, have been making pre-Budget speeches
The message to the suburbs, provincial cities and small towns is that National has been in charge for nearly seven years, yet most people do not feel better off.
If this is as good as it gets, then National's policies are not working and a new approach is needed.
The two speeches were notable in having the Prime Minister in their sights rather than English.
The blunt fact is that if Labour is to have a chance of winning the 2017 election, it has to implicate John Key as a poor economic manager.
Planting doubt in voters' minds about National's economic competence will not happen overnight. It is a slow-burner.
The challenge facing National on Thursday is to deflect this attack by presenting a Budget with fresh ideas and innovative policies.
National must avoid looking tired and like a third-term Government playing safe and merely going though the motions.
First-term governments get criticised for packing too much in their Budgets; third-term governments get crucified for not having enough in theirs.
English's seventh Budget potentially has far more significance than what might first appear to be the case.