TORONTO -- Education Minister Stephen Lecce called on Ontario's major teachers' unions to enter into mediation Monday, as one took another step toward a potential strike and another voted overwhelmingly in favour of one.

Disagreements remain at the table on key issues, including compensation, Lecce said, and having an independent, third party would help reach deals. The offer comes as Lecce accused the unions of escalating the labour dispute.

"I think when you speak to families though, they perhaps wouldn't see escalation today or over the last several weeks -- every week without exception, pretty much -- as particularly constructive to keeping the parties at the table," he said.

"My interest is to get a good deal for kids that keeps them in school ... I can't be the only person in the room who gets the sense that there's a trajectory that some unions are on right now. That is a fair point. If we know that's their trajectory, how can I help stem that?"

Three of Ontario's four major teachers' unions are taking steps toward potential strikes as they negotiate with the government for new contracts. They all said Monday that they were open to mediation, with the union representing elementary teachers saying that a conciliation officer in their talks was already acting in the role of a mediator. The English Catholic teachers' union lamented that Lecce made the offer through a news conference, and not at the table.

The Ontario Secondary School Teachers' Federation announced Monday that high school teachers voted 95.5 per cent in favour of a strike. The OSSTF is already in a legal strike position, though it's also required to give five days' notice before a strike and has not yet done so.

Union president Harvey Bischof said they have talks scheduled with the province through to Thursday, and he is hoping significant progress can be made.

But, he said, there are still major outstanding issues -- including the government is still proposing one per cent raises, when the union is asking for inflationary increases, which would be around two per cent -- as well as raising class sizes and implementing four mandatory e-learning courses.

"They are still talking about raising average class sizes to 25:1 -- at the same time they've proposed and have not taken off the table that all class size caps around the province should be eliminated," he said.

"The only limit would be the number of kids you could stuff into a particular room."

Ontario's Catholic teachers said Monday they have filed a request for conciliation in their talks, which is one step in the process toward being in a legal strike position.

The government is insisting on drastic cuts, and has demonstrated "a total lack of understanding or respect for the bargaining process," the Ontario English Catholic Teachers' Association said in a statement.

"Catholic school board trustees have come to the table prepared to work constructively, but the government side is in complete chaos," president Liz Stuart wrote.

"Since this round of bargaining began, the government has been going out of its way to derail the process. They have made comments through the media that have had a detrimental effect on negotiations, introduced regulations and legislation that violate our collective bargaining rights, and played games with the public to muddy the issues and deflect blame."

Negotiations between the province and the education unions started on tense terms a few months ago amid government moves to increase class sizes, and recent legislation limiting raises for all public sector workers to one per cent per year for three years has further angered teachers.

Elementary teachers are set to start a work-to-rule campaign on Nov. 26 that they say will target ministry and school board administrative tasks and will not affect student learning.

Negotiations between the province and French teachers continue.

This report by The Canadian Press was first published Nov. 18, 2019.