The New Zealand Educational Institute (NZEI) has warned primary school teachers and principals could take "indefinite strike action'' if the next round of negotiations with the Ministry of Education fails.
The country is expected to experience severe disruption when both primary and secondary school teachers strike on May 29, but NZEI campaign director Stephanie Mills said if the ministry did not provide a suitable offer, primary schools could take industrial action up another gear to indefinite strike action before term 2 was finished.
It meant primary schools across the country would close until an offer was agreed.
Ms Mills said it was one of several options being debated by NZEI union members at present.
The other options were another one-day strike, a three-day strike, rolling strikes (where schools in certain regions go on strike), or work-to-rule.
"If negotiations don't succeed, we may need further industrial action and we've asked members to give us feedback on what they think would be most effective, and what they could commit to.''
She said the options were presented to primary school staff around the country on Sunday, and it was still too early to say what their preferred option was.
"he national executive will make a decision some time after May 29 about which option will be taken.''
Otago Primary Principals' Association chairman and Elmgrove School principal Chris McKinlay said it was still too early to get "a reading'' on whether primary teachers would support an indefinite strike or not.
"It would definitely be a very difficult stance for teachers to take, in terms of the financial burden of doing that.
"If the teachers do actually vote for that, it would really indicate how strongly they feel about this.
"We're a year into these negotiations. We've come too far to stop now.
"They need a little bit more traction on their claims.''
Southland Primary Principals' Association president and Ascot Community School principal Wendy Ryan said the level of frustration among teachers and principals was so high, she believed an indefinite strike was "a goer''.
"People are feeling really disrespected, they feel their goodwill is going absolutely un-noticed, and people are failing to realise we are in a crisis situation in education.
"We've had a teaching shortage since 2013 and we're still in this place.
"Quite frankly, older teachers are exhausted, they've given their all to teaching and they just feel like no-one's listening to their concerns.
"The bottom line is, it's about the lack of teachers, it's no longer a first choice career for people going into the workforce, and the people that do are only staying for five years.''
She said parents should be really concerned about the issues.
"You want to have the best people teaching - people who really want to be there. You don't want people that are thinking, `oh well, what else can I do'.
"An indefinite strike is a viable threat.''
Otago Chamber of Commerce chief executive Dougal McGowan said an indefinite strike would have a major impact on the local economy.
One of the ways businesses could ameliorate the effects of the industrial action was to allow staff to work from home, where possible, so they could look after their children.
"But for some businesses, it will be harder than others. If you work in hospitality, manufacturing or engineering, you can't work from home.
"It will have an economic effect on businesses because employees will have to take unscheduled time off work.
"And there will be flow-on effects because the time parents use for the strikes, may be time they have to take from Christmas leave. They may have to take unpaid leave.''
The Post Primary Teachers' Association has similar strike plans in place for secondary schools if negotiations failed following May 29.
A spokeswoman said secondary teachers voted last week to take rolling strikes between June 17-21, followed by four weeks of "rostering home'' where a different year level would be sent home for a day.
Dates for the rostering home strikes had not yet been decided, but it would happen in term 2, she said.
"Our preference is to not strike at all, but I think the ball is in the Government's court at this point.''
