The Progressive Conservatives are urging the government to impose new contracts on teachers before students come back to school next week.
Opposition Leader Tim Hudak says the governing Liberals aren't using the power they have under a controversial new law to stop disruption in public schools, which have seen teachers stage rotating one-day strikes.
Mr. Hudak says the Liberals owe it to parents to take action before students head back to class.
Education Minister Laurel Broten has said that she has the option to impose new contracts on teachers under Bill 115, which also gives the government the power to stop strikes and lockouts.
She is expected to speak about the dispute on Thursday, two days after the cut-off date for the unions to reach local agreements with school boards.
The Elementary Teachers' Federation of Ontario has offered not to stage any more strikes if the Liberals agree not to impose new contracts on them until a new premier is chosen later this month.
They walked out of class in protest of the new law, which gives the government the ability to force a new contract on them that would cut their benefits and freeze the wage of most teachers.
So far the government has held off, but the unions have warned that there will be more disruption if the Liberals impose new contracts.