Ontario's Liberals plan to make full-day daycare free for children aged 2-and-a-half until they are eligible for kindergarten should they form government after the June election, Premier Kathleen Wynne said on Tuesday.

The program would begin in 2020 and come at a cost of $930 million to the province. The move is part of a larger, "historic" $2.2-billion investment to expand access to licensed childcare for families.

"Not being able to find or afford child care is stressful. It is troubling, and it is holding families back at a time when it is already hard enough to get ahead," said Wynne, who was joined by Finance Minister Charles Sousa and Indira Naidoo-Harris, minister responsible for early years and child care and minister of education.

"No more anxiety about costs ... The freedom to choose when it's time for mom or dad to go back to work. This is a big change," Wynne said. "We're playing the long game here, folks. This is the investment in the people of this province."

Wynne made the announcement to a room of parents and children at Nelson Mandela Park Public School in Toronto, saying more details about the promise are coming in Wednesday's pre-election budget.

According to Wynne, the plan would save the average family with one preschooler some $17,000. In Toronto, where the average cost of daycare is more expensive than any other Canadian city, families would benefit even more, she added.

Growing list of Liberal promises

The policy was largely devised by Gordon Cleveland, a University of Toronto economist, who called the current daycare regime a "punishing financial burden" for families. Cleveland said his research shows that yearly daycare fees for Ontario families, on average, range between $10,000 to $22,000 depending the age of children and where they live.

The typical family with one child between the age of two and four uses more than 23 per cent of its after-tax income to pay for child care, Cleveland explained.

"Making child care free for preschool children will be transformative for Ontario's families; it will help families balance the demands of work, education and family life, and will dramatically improve affordability, especially for children in low and middle income families," Cleveland said in a statement issued to reporters.

The Liberals also committed $162.5-million over three years to boost access to licensed care, decrease fees and reduce wait list for parents applying for fee subsidies. Furthermore, a Liberal government would introduce a wage grid for early childhood educators to bring their compensation to the level of peers working in the school system.

Other elements of the plan include funding specifically for First Nations communities and $90-million to continue increasing the number of child care spaces in Ontario. In 2016, Wynne pledged to build 100,000 new spots for children under four by 2021.

Ontario's Liberals have rolled out a number of costly commitments in the run-up to the release of the 2018 budget. Last week, Wynne revealed that OHIP+ will be expanded to include all Ontarians 65 and over, and promised extensive new funding for hospitals. Yesterday, she pledged $300-million for special needs education.

The provincial election is set for June 7.