A union representing Toronto's inside workers has been given the green light to launch a strike, but leaders say they have no plan to do so just yet.

CUPE Local 79 President Tim Maguire said union members voted in "historic numbers" on Tuesday to give the union the right to walk off the job, beginning after midnight on Saturday, March 24.

Macguire says the union does not plan to strike, but needs to be ready in case the city plays dirty after the negotiation deadline. Toronto is allowed to impose its own terms if a deal isn't reached by the deadline – a rare step which was also threatened during recent negotiations with another union.

"We asked for that mandate in the case that the city chooses to strip basic, fundamental working rights from our members after the deadline at 12:01 a.m. on Saturday morning," Maguire told a press conference on Wednesday.

"If the city were to take the move to threaten and carry through with stripping fundamental employment rights from our members, we would have to consider other actions at that point."

The 23,000 inside workers include child care workers, ambulance dispatchers, nurses, janitors and parks and recreation staff. The union did not release the number of members that cast ballots in Tuesday's strike vote, but said they received "overwhelming numbers."

During the press conference, Maguire reiterated several times that his members would not walk off the job if there is not a new deal in place by the deadline. But they needed to be ready.

"It is important to remember the services our members provide, the breadth of services affecting all Torontonians – child care, building permits, recreation programs, employment and social services," he said.