Teachers' unions are being reasonable in their demands for more money given the "huge expectations" the government raised, National Party leader Simon Bridges says.
Primary and secondary teachers will walk off the job on 29 May in what will be the largest industrial action taken by teachers.
Education Minister Chris Hipkins said the strike was unjustified given the size of the offer on the table, and said there was no more money for teacher pay claims.
Mr Hipkins is also laying the blame for the impasse at National's feet, saying there was "gross mismanagement of the sector over nine years" and that the previous government "bottled it" by failing to tackle the serious problems in the sector.
National Party leader Simon Bridges said the government was left with growing surpluses and had spent billions on policies such as the fees free policy and the provincial growth fund.
"The teachers are reflecting that sense of 'there's money for other stuff and we want our share'."
The government had set "huge expectations", he told Morning Report and was "spraying money around" on other things.
Mr Bridges said when his party was in power it faced the global financial crisis and the Canterbury earthquakes - but this government has more room to move.
Teachers didn't strike at that time because they knew the circumstances the government was in, he said. "Now what they understand is a government that talked a big game, and a government that has [inherited] growing surpluses."
NZEI president Lynda Stuart rejected Mr Hipkins' statement that the strike was unjustified saying there was a crisis within education because it was difficult to attract people to work in the profession.
"We don't want to take strike action - none of our members want to do this, Ms Stuart told First Up.
"We need to see an improved pay, we need to see support for workload and also support for those children with additional learning needs.
"The package that we've had delivered to us is actually not going to do that. There are some parts to it that will certainly help - not denying that - but ... it is just not enough."
If teachers had accepted the latest offer from the government they would have lost pay parity with their secondary colleagues, she said.
Mr Hipkins said yesterday for most primary teachers, the government's offer would result in an extra $10,000 a year pay increase. For secondary school teachers, the amount was slightly smaller, but there were other benefits, including money already committed to further support for teachers and recruitment, he said.
The government valued teachers, he said. This was demonstrated by the fact the offer would put most teachers, primary and secondary, in the top 20 percent of income earners in New Zealand, and almost all principals in the top 10 percent.