For breaking news on CUPE's deal with the provincial government, click here.

The following story is from before the deal was struck.

A decision on whether or not Canadian Union of Public Employees education workers will stage a provincewide strike is imminent, according to Ontario's education minister.

The union and government have been locked in last-minute negotiations all of Sunday.

CUPE served notice on Wednesday that some 55,000 members, from office administrators to special education assistants to custodians, are prepared to walk off the job Monday if a deal can't be reached by midnight. That notice was issued two days into a work-to-rule campaign.

As of 5:30 p.m. Sunday, a media blackout remained in place, although a CUPE spokesperson said negotiations are ongoing.

A strike by education workers would see the cancellation of many classes and all recreational and after-school programs starting Monday.

We are working as hard as we can to get a deal done. - Ontario Premier Doug Ford

On Thursday, school boards across Ontario sent notices to parents, warning that without custodians, clerical staff, education assistants and others on site, they cannot guarantee students' safety and would be forced to close their doors.

The following school boards across Toronto and its suburbs are among those expected to close:

Toronto District School Board (TDSB).

Toronto Catholic District School Board (TCDSB).

Peel District School Board.

Dufferin-Peel Catholic District School Board.

York Region District School Board.

York Catholic District School Board.

Halton Catholic District School Board.

Durham District School Board.

Durham Catholic District School Board.

The TDSB is Canada's largest school board, serving roughly 246,000 students at 582 schools. Meanwhile, about 90,000 students would be affected in the TCDSB.

A group of OPSEU members gathered in front of the Sheraton Centre to show support for CUPE members. (Keith Burgess/CBC)

Hundreds of thousands of students provincewide will be impacted if planned disruption is not averted.

Union leaders and parents rally

As the negotiations continued Sunday, a group of people, including union leaders and parents, gathered outside the meeting venue at Sheraton Centre on Queen Street West.

The Ontario Public Service Employees Union (OPSEU), which is leading the rally, said they are standing in solidarity with CUPE in their ongoing efforts to reach a deal with the province.

OPSEU president Warren (Smokey) Thomas said full-time and part-time support staff who were already downtown for another meeting joined the rally.

"We represent education workers as well.… Not only are we out in solidarity and support, but what happens with CUPE certainly would have a profound impact on our bargaining," said Thomas, whose own union will be heading into bargaining talks on Nov. 14.

<a href="https://twitter.com/CUPEOntario?ref_src=twsrc%5Etfw">@CUPEOntario</a> OPSEU CAAT-Support staff showing solidarity with CUPE Education workers <a href="https://t.co/QLYtDmh6YI">pic.twitter.com/QLYtDmh6YI</a> —@justabitofme

Thomas said he wants the government to know that their fight with CUPE goes beyond just one union.

"They're picking a fight with a much bigger group than CUPE," Thomas told CBC News. "All unions will stand with CUPE."

Toby Molouba, a teacher, attended the rally with her son and daughter. (CBC)

'The uncertainty is challenging for everybody'

Teacher Toby Molouba said she decided to join the rally Sunday, even though her kids' school will be open on Monday.

"I don't think it will be open very long and we just want to support the workers. I absolutely feel for parents that are having to make arrangements for tomorrow and beyond. The uncertainty is challenging for everybody," she said.

"Sometimes it's helpful to take action, so I would encourage parents to be really informed as to what the concerns are and try and understand what CUPE workers in their children's school are doing on a day-to-day basis."

A group of people, including union leaders and parents, gathered Sunday outside the meeting venue at the Sheraton Centre on Queen Street West. (Keith Burgess/CBC)

Meanwhile, TCDSB chair Maria Rizzo told CBC News that the decision to close schools is based on an assessment of health and safety considerations related to the needs of all students.

"We are really, really worried about special needs kids, especially those that require one-to-one supervision and care by education assistants, and we're worried about the health risks, about lead in the water if the pipes aren't flushed, the accumulation of garbage," Rizzo said.

"These are our support workers and they make our schools function so that kids and staff are safe and kids can learn."

Hope for a last-minute deal

The TCDSB chair said they are communicating with parents through an automated system called messenger.

"We've written a letter, informing the parents that we are closing the schools if there is a strike," Rizzo said.

Principals, teachers and all non-union staff are expected to report to work, she added.

TCDSB chair Maria Rizzo says the decision to close schools is based on an assessment of health and safety considerations related to the needs of all students. (Sue Goodspeed/CBC)

On Friday, Lecce said there's still hope for a last-minute deal with CUPE workers. However, reaching an agreement will require the union to back down from what he calls an "unprecedented" escalation in job action.

Media blackout

Late on Saturday, CUPE said there would be no further communication from the union as the parties continue to negotiate.

"The parties have agreed to a media blackout for the duration of negotiations in order to focus on reaching a settlement," spokesperson Mary Unan wrote in a statement.

Ontario Premier Doug Ford, who attended a ceremony on Sunday for fallen firefighters, pointed to the blackout when asked for a comment on the negotiations.

"We are working as hard as we can to get a deal done," he said.