Daniel Legere says he fears that the government will try to privatize many services such as plowing roads.
The Liberal government is looking for ways to cut departmental budgets by up to 10 per cent and is holding meetings with various groups this week, but unions were not invited.
Legere says many of the union's 30,000 members are frontline workers and should be consulted.
The union held a noon hour rally in front of the provincial legislature.
The government has repeatedly said it needs to find up to $600 million in cuts and new revenue in an effort to eliminate a structural deficit.