"Now is the time for action.
"We've got a serious problem and it needs addressing," he said yesterday after Education Minister Anne Tolley threatened to sack primary school boards which allowed their teachers to boycott the system.
From February next year, schools have to measure students against benchmarks for reading, writing and maths and report to parents.
The system has come under fire from teacher unions and academics concerned at the speed of its implementation and the effects it could have on children who are falling behind.
Unions have threatened boycotts and industrial action, believing the system could lead to "league tables" which compare the performance of schools.
"The future of young New Zealanders rests on this," Mr Key said at his post-Cabinet press conference.
"We've sat back for decades now, with 20% of young New Zealanders leaving school with inadequate literacy and numeracy skills."
Mr Key said the Government had two options - address the problem, or do what other governments had done and fail to step up.
"I personally believe that unless you measure, monitor and report something, you won't effect the change that you need."
Mr Key said he would prefer not to see boards sacked.
"We want to work constructively with principals and teachers to see the successful rollout of national standards."
Mrs Tolley said that in extreme cases she would dissolve school boards and appoint commissioners.
"In the end, I would have to do that.
"I don't think it would come to that, but I would do it.
"You just cannot have schools disobeying the law," Mrs Tolley said.
Labour's education spokesman, Trevor Mallard, said a trial period would provide information about whether the scheme was a good way to go.
"I'm surprised she's putting herself into that corner.
"She does have a choice," he said.
Primary teachers' union the NZEI said Mrs Tolley's position was disappointing.
"The way she is approaching it is like she's got herself into a corner and can't find a way out without losing face," NZEI president Frances Nelson said.
A meeting of 80 Northland principals last week unanimously agreed not to implement the standards until their effect was better known.
