HALIFAX -- Nova Scotia's education minister says it's "full steam ahead" with a proposed expansion of pre-primary classes for four-year-olds, brushing aside opposition critics who are calling for a one-year delay to ensure adequate staffing levels.

The Progressive Conservatives and the NDP said Monday that the lack of information around such things as staffing and curriculum so close to the beginning of the school year means consultation is needed to ensure the program is sound.

But Education Minister Zach Churchill made it clear the government won't be backing away from what was a key commitment during last spring's election campaign.

"This is full steam ahead," said Churchill of a rollout targeted for completion by the end of September.

"This programming is too important for our kids for us to delay the rolling-out of it. We are going to push as aggressively as we can to get this program going and we are going to tackle each challenge that arises as we move forward."

The pre-primary program is to be introduced across the province over the next four years at a cost of $49.9 million a year.

In mid-July, Churchill announced a list of 30 new classrooms that would be added to 20 existing classes at 43 locations across the province, but he also warned that staffing would pose a "challenge." He also made it clear that class availability would be contingent on the numbers of available early childhood educators.

The province's eight school boards are responsible for hiring -- a process Churchill said is still ongoing, with applicant interviews scheduled for this week. The government plan requires one early childhood educator for every 10 children in a class, with a maximum of 24 children per class.

"We will know by the end of next week if we are able to have a full complement of staff to roll this program out at every site in the fall," he said. "Obviously, we are not going to be opening up a site if the qualified early childhood educators are not hired to do that."

Tory education critic Tim Halman said the system would be better served if the government held off on pre-primary's expansion until next fall.

"I sense that this is a government that's moving too quickly to fulfil a political promise rather then focusing on building a pedagogically sound program," said Halman.

NDP education critic Claudia Chender said taking "a step back" would also give the government an opportunity to minimize the impact on private, non-profit providers who fear losing staff to the public system.

"It's happening too quickly with no consultation and as a result everyone ... is pretty much left in the dark and that's a pretty challenging place to be when you are rolling out a major program," said Chender.

Last week a veteran private provider expressed concern on the potential loss of staff to the public system.

Pamela Streeter, who runs several early education programs including pre-primary at Creative Kids Education Centre in Hammonds Plains, also said the uncertainty was creating problems for parents who are trying to plan child care.

The government has promised consultations for the fall, talks Churchill said would move ahead.

"I know there is stress in that sector right now, said Churchill. "In order for this to work ... we do have to be working in concert with one another."