The Liberals, Quebec Solidaire, and Parti Quebecois, are all voicing their opposition to the Legault government's plan to provide free pre-k classes to four-year-olds.
The CAQ tabled legislation, Bill 5, which would require all school boards to provide the service.
20,000 supporters have already signed a petition opposing it.
Montreal-area daycare providers plan to try and garner more support for the petition by asking parents to sign it when they drop their kids off.
The Quebec council of early childhood education services (CQSEPE) is liaising with the union which represents daycare workers (FIPEQ-CSQ) to try and get more parents to sign the petition before the March 12 deadline.
The petition says the government should ensure children have the "essential skills for successful entry into school at age five," instead of focusing on pre-k classes for four-year-olds.
Premier Francois Legault argued that having four-year-olds in classes would allow schools to hire more specialists, such as social works, psychologists, and speech therapists.
He added that children with learning difficulties could overcome them more easily if they started school earlier.
"We can certainly share a bigger team when we have a whole elementary school rather than when we have just a daycare," he said. "It seems obvious."
The provincial government said it would invest $400 to $700 million to make the classes available to all four-year-olds in the province.
"We need to back up and say, is this really where we need to spend our money today?," said Liberal MNA Jennifer Maccarone.
Legault said the classes would not be compulsory.