The bill would rein in compensation, but also give the government the power to ban strikes and lockouts for two years.
The Elementary Teachers' Federation of Ontario says the legislation is unnecessary and tramples on their constitutional rights. The Liberal government argues that freezing teachers’ wages is necessary as the province tries to pare down a $15-billion deficit.
The bill is likely to become law, as the Progressive Conservatives have agreed to support the bill.
Three unions who oppose the province's demands say they will take their fight to the Supreme Court if necessary while the Liberals say they believe the legislation can withstand a constitutional challenge.
“We need to take a pause when it comes to teacher pay increases,” said Education Minister Laurel Broten on CBC News Network. “If this legislation is challenged [in court], we will defend it.”
The teachers' federation has issued a call for teachers and school workers to join Tuesday’s rally but many teachers also say they will work to defeat the Liberals in two key byelections scheduled for Sept. 6.
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.
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.
The Liberals need to win both of the seats up for grabs in the Sept. 6 byelections in order to secure a majority. They currently control 52 of the 107 seats in the Ontario legislature, while the Tories hold 36 seats and the New Democrats have 17.