The minority government introduced a controversial bill that would force new contracts on teachers and school workers, as well as give the Liberals the power to ban lockouts and strikes for at least two years.
It will likely become law, as the Progressive Conservatives have agreed to help pass the legislation.
But the price may be steep for Ontario's self-described "education premier," whose austerity efforts have alienated influential groups whose support — both political and financial — has helped the Liberals hold on to power for nine years.
It may cost Premier Dalton McGuinty his shot at a majority government in two potentially game-changing byelections set for Sept. 6, with the unions now channelling their efforts into defeating the Liberals.
The Elementary Teachers' Federation of Ontario — representing 76,000 members — said it's calling on all teachers to volunteer in the riding of Kitchener-Waterloo, which was previously held by the Tories.
"Let's be honest, there's no option for us here," said union president Sam Hammond.
"Our members are pointing in the direction they want to go, and our members across this province feel absolutely betrayed by this government based on the work and the partnership that we've had since 2003."
The Liberals want the bill passed before the end of the week, saying it's the only way to ensure labour peace before students head back to the classroom.
But the unions and the New Democrats insist the school year was never in jeopardy and say the Liberals are manufacturing a crisis in a desperate bid for a majority.
McGuinty dismissed the accusations while visiting a family home in Waterloo with the Liberal candidate.
"This is a lot bigger than any one byelection," he said. "It affects two million students and 125,000 teachers."
It's important that voters consider the Liberals' approach to the issue in contrast to the two other parties, who are swinging too far to the left or right, McGuinty said.
"But the fact of the matter is, this is of real interest and concern to parents everywhere."
A few hours before the bill was introduced, the Ontario Secondary School Teachers' Federation announced it was postponing strike votes that the education minister had used to bolster her argument that job action was imminent.
The federation is making progress bargaining with school boards and won't need to go ahead with the votes unless a board seeks conciliation, said president Ken Coran.
"We said from Day 1 that our teachers, our educational workers would be in the classrooms," he said.
"They were using the strike vote as maybe a bit of leverage to confuse the public. That is certainly not the case, it was never the case. So by postponing the strike votes, I think the message is very clear that we're sincere about our position."
But the other two unions are making no promises, with strike votes starting in mid-September. They're organizing a rally Tuesday at Queen's Park to protest the legislation.
They said there will be no labour disruptions this fall, but aren't ruling out job action later in the year. Teachers can also decide not to volunteer for extracurricular activities, such as coaching sports teams.
Union hopes that they could prevent the legislation from being tabled were dashed last week when the Conservatives lent their support to the bill.
The new alliance has prompted plenty of grandstanding from the Tories and Liberals, who are both claiming credit for the austerity measures.
Opposition Leader Tim Hudak crowed that the Liberals had finally seen the light on forcing wage freezes after months of Tory preaching. But while he'd prefer similar legislation for all public-sector workers, he'd take what he could get.
And while his party will press for changes to the bill, Hudak said he won't use his clout to force the amendments, because his party prefers to stand on its principles rather than engage in horse-trading.
But he wouldn't say whether the Tories will vote in support of the bill or remain in their seats, which would still allow it to pass.
The Liberals claimed higher ground, saying they amended the bill for the Tories in the spirit of compromise. But it won't make any difference, because they plan to impose the measures that they took out — involving hiring procedures and diagnostic testing — through regulation instead.
While teachers, students and parents brace for the upcoming school year, it's still unclear how quickly the legislation will wind its way through the legislature.
The Liberals recalled the legislature two weeks early to introduce the bill. If it doesn't go through, old contracts with teachers will automatically roll over Sept. 1, giving them pay raises and benefits this year that the province can't afford, they said.
Three unions representing about 45,000 workers, including English Catholic and francophone teachers, have signed on to an agreement that includes three unpaid days off and ends the practice of banking sick days that can be cashed out at retirement. But three other unions representing 191,000 workers oppose the deal.
Other provinces have also run into trouble while trying to clamp down on public sector compensation.
British Columbia's yearlong labour dispute with teachers saw them refuse to perform certain administrative tasks, such as filling out report cards, as well as a three-day walkout that shut down classes.
The B.C. Liberals passed back-to-work legislation and sent the talks to mediation, which is now the subject of a court challenge.
Education Minister Laurel Broten said the Ontario government is confident its legislation would withstand a constitutional challenge by the unions, who've vowed to take their fight all the way to the Supreme Court of Canada.