In a video posted early Friday morning, McGuinty thanked teachers for their years of work before asking them to accept a "real two-year wage freeze" and changes to their sick leave plan.
"While education funding will still grow, we're going to have to focus on things that allow our children to achieve the best possible results," the premier said.
"Because salaries account for most of that education funding, we're going to be asking all those working in education to do their part to help us slow down spending."
The video is another attempt by the Liberals to negotiate through the media, which will hurt the province and students in the end, the opposition parties said.
"I think that the proper thing for a leader to do in these circumstances is to negotiate at the negotiating table," said New Democrat Peter Tabuns.
"Having a premier who goes into his office, closes the blinds and makes YouTube videos is not showing leadership."
The Progressive Conservatives, who want the province to force a wage freeze on more than a million workers in the broader public sector, say they doubt the Liberals will actually freeze teachers' pay.
The teachers' unions were among the groups that banded together under the umbrella Working Families Coalition and spent millions of dollars to ensure McGuinty was re-elected last fall, said Conservative Peter Shurman.
"It must be rather hard for McGuinty to put out a YouTube video like that for an audience that has participated in funding an effort to the tune of about $9 million during the election campaign aimed at defeating us," he said.
Ontario teachers currently start at $41,766 to $44,292, and can make up to $92,813 in elementary schools and $94,942 in secondary schools, depending on years of service and education.
The government wants to freeze the grid so no one gets a raise because of seniority or improved credentials.
The premier is also asking teachers for an end to a "generous sick leave plan" which currently allows most teachers in Ontario to bank up to 200 days over their career, leading to a lump sum payment averaging $46,000 when they retire.
The governing Liberals want to limit teachers to six sick days a year and eliminate their ability to accumulate them and be paid out, although sick days that have already been banked will be protected.
Education Minister Laurel Broten has said teachers' sick days currently amount to a $1.7-billion liability and can't be sustained by a government facing a $16-billion deficit.
The Elementary Teachers' Federation of Ontario has called the details of the government's position "offensive" and walked out of contract talks on Wednesday.
McGuinty's video urges teachers to work with the government to safeguard the education of Ontario's youth as the province weathers a tough global economy.
"Getting there won't be easy. It's going to take an unwavering commitment and we need to make the right choices for our students," he said.
"If we work together, we can keep advancing student achievement so that we preserve our greatest advantage as a province, that's our highly skilled, highly educated workforce."
Contracts for teachers and school support staff expire Aug. 31, and the government is seeking only a two-year deal after going for four-year agreements in the last two sets of negotiations.
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