The Toronto Transit Commission's largest union has called a news conference for Thursday morning, one day after telling the media that contract talks with management had come to a "boiling point."

The Amalgamated Transit Union Local 113 has said it will give Torontonians at least 48 hours notice before public transit workers go on strike.

The news conference is expected to take place at 11:30 a.m. The union is not saying what they will announce as it will depend on how the talks progress on Wednesday, someone close to the negotiations told CTV.ca.

There is speculation among workers a strike deadline will be set for Monday, CTV Toronto's Naomi Parness reported.

On Thursday, TTC chairman Adam Giambrone said he's hopeful both sides can keep talking and avoid a labour disruption.

"It's been a little bit more difficult (in recent days) than we've had over the past week, but we're committed at staying at the (negotiating) table," Giambrone told CTV News.

Both sides have been at the negotiating table since late March trying to hammer out details of a new contract. The ATU and two smaller unions have been in a legal strike position since April 1.

A TTC source told The Globe and Mail on Tuesday that management was making its position clear.

"It's coming to the boiling point. ... It's decision time," the source said.

Last Thursday, union president Bob Kinnear told reporters he didn't believe the two sides could come to a deal as long as the TTC's general manager Gary Webster was leading the negotiations.

He said Giambrone has been much more receptive to the union's needs and suggested he replace Webster on the negotiating team.

Giambrone was quick to respond that management had full confidence in their negotiating team.

The contentious contract issues have to do with "reallocating" funds from the provincial health premium to top up other benefits.

Kinnear used last week's news conference as an opportunity to urge the provincial and federal government to step in with financial support to take the burden off TTC workers.

He also said any job action would be an all-out strike, not a work-to-rule campaign as had been suggested in recent weeks.

The ATU represents 8,500 drivers, ticket collectors and maintenance workers.

If they were to go on strike, it would effectively cripple public transit in Toronto, stranding millions of commuters.

With a report from CTV Toronto's Naomi Parness