While Ontario Premier Doug Ford's government managed to reach a last-minute deal to avert a strike by school support workers, far tougher rounds of education bargaining loom ahead.

Getting a tentative agreement with CUPE's 55,000 education workers took on added urgency for the Progressive Conservatives as their federal cousins feared the political consequences of widespread school shutdowns in battleground Ontario at the height of a federal election campaign.

The Ford government is coughing up an extra $100 million a year as part of the deal, including new funding for support staff jobs and a wage increase. That prompted union president Laura Walton to thank Education Minister Stephen Lecce for "opening the piggy bank."

To get a deal with teachers without a strike, Lecce and Ford will likely need to open that piggy bank a whole lot wider.

The amount of money involved makes contract talks with the province's teachers' unions much more challenging than with CUPE.

Lecce arrives at a news conference to announce a tentative contract deal with CUPE's 55,000 school support staff. (Cole Burston/The Canadian Press)

There's a nearly $1-billion bargaining gap between the province and the three main teachers' unions: the Ontario Secondary School Teachers' Federation (OSSTF), the Ontario English Catholic Teachers' Association (OECTA) and the Elementary Teachers' Federation of Ontario (ETFO).

That gap is predominantly about staffing numbers, mainly at the secondary level. The fundamental issue at the table is the government's plan to increase average class sizes, which would mean some 10,000 fewer teaching positions four years from now than if class sizes remained the same.

The bulk of those reductions would hit the secondary school teaching force, currently at about 42,000.

OSSTF's publicly released bargaining stance calls for keeping class size averages at last year's status quo.

Increasing class sizes as proposed would save the government $900 million a year, according to the province's independent Financial Accountability Office. That's the chief ingredient in the $1-billion gap between the two sides.

There are about 110,000 teachers in Ontario right now, and their total yearly compensation costs the province about $11 billion. For a government that wants to cut costs, the teaching force is a big, natural target. For comparison's sake, the annual wage bill for CUPE's 55,000 education workers is roughly $2 billion.

Charles Pascal, a former deputy minister of education, predicted the CUPE deal before the weekend's marathon bargaining session began.

2reasons Min <a href="https://twitter.com/Sflecce?ref_src=twsrc%5Etfw">@Sflecce</a> will cave&settle w CUPE &avoid strike<br>1) claims victory 4students & acts the hero while preparing to be tough w <a href="https://twitter.com/hashtag/ETFO?src=hash&ref_src=twsrc%5Etfw">#ETFO</a> & <a href="https://twitter.com/hashtag/OSSTF?src=hash&ref_src=twsrc%5Etfw">#OSSTF</a> 2) Strike next week not good 4 Prem’sBFF Scheer. So things will be settled Sat or Sun &Minister will run to front of the parade. —@CEPascal

Pascal now predicts the Ford government's negotiations with teachers will not go so smoothly.

"The ETFO and OSSTF negotiations are going to be extremely difficult," said Pascal, who also advised the McGuinty Liberal government in its creation of full-day kindergarten. "It's going to be much more difficult because there's much more at stake for the government."

In an interview, Pascal said getting a deal with CUPE was "fiscally speaking low-hanging fruit," a move designed to make the public perceive the Ford government as reasonable on education.

He said bargaining with teachers will test the government's claims that it's fiscally prudent while caring about the interests of kids in school.

Last week, Lecce publicly raised concerns about the significance of sick days to education system costs, and portrayed that as a key sticking point in the CUPE negotiations. Yet the tentative agreement leaves CUPE's sick pay formula intact, and the only concession the province achieved is requiring a doctor's note for short-term disability absences.

The Ontario Secondary School Teachers' Federation (OSSTF) has made its bargaining position public. The union is proposing a contract deal that would halt planned increases to the average high school class size. (Megan Thomas/CBC)

Lecce is already shifting his tone about cutting costs through bargaining. "This has never been a fiscal exercise, really it's been about how we can reprioritize our investments to help your child," he said in an interview Monday on CP24.

This could be in part because the province's fiscal situation is nowhere near as dire as the Ford government long claimed. The 2018-19 deficit was revealed last month to be $7.4 billion. In the first few months of this year, the government was pegging the figure at nearly twice that: $14.5 billion. This means the PCs have some financial wiggle room and could get to a balanced budget during their mandate without curtailing spending so drastically.

CUPE got its deal in no small part part by leveraging the federal election, exploiting Ford's desire not to feed the Justin Trudeau-driven campaign narrative that Conservatives are bad for schools.

That particular political dynamic won't be in play at the teachers' unions bargaining tables. None of the teachers' unions will be in a legal strike position before election day on Oct. 21.

The key question for when teacher bargaining hits crunch time: how much will Ford and Lecce be willing to spend to achieve their stated goal of keeping kids "in the classroom, where they belong"?