Junior doctors could walk off the job over an hours dispute, causing major disruption to hospitals.
The New Zealand Resident Doctors' Association (NZRDA) is moving to formally ballot its members.
NZRDA national secretary, Dr Deborah Powell, says recent polling has shown strong support.
"The vast majority of our members have already indicated that they will take strike action and at the moment we are formally confirming that with them."
The result of the ballot will be known on Monday.
The dispute involves junior doctors' working hours - they want to cut their 12 day stretch down to 10, and their seven night roster down to four.
Dr Powell says doctors are making mistakes because they're too tired.
"Doctors want to practice safely, they want their patients to be safe, they want to be safe."
DHBs say they're keen to implement a safer rostering process, but add that it's unreasonable to expect the same pay for fewer days.
"DHBs have agreed to alternate rosters that remove the 12 day stretches, but they cannot agree to rosters which include paying the RMOs for days off," says Julie Patterson, Lead CEO for the 20 DHBs' Employment Relations Programme.
"A second effect of reducing the 12 day stretches, is that the RMOs may need to work more weekends," she says.
At the moment the maximum they can work is every other weekend, and many work just one in three.
Ms Patterson says they "can't make progress while both of those clauses remain".