While city officials say they are in the dark about what triggered negotiations to collapse between its representatives and CUPE Local 101, the setback is taking a toll emotionally on those involved.

The Local president, Shelley Navarroli, was in tears at strike headquarters. Some striking workers also made hand gestures to a reporter.

“I think the moves we made were the strongest efforts, thus far, and quite frankly, I don't see how we could go any further,” Navarroli says.

The unresolved issues include job evaluation, promotion policies, early retiree benefits for new employees and hours of work.

On Monday, the mayor said in a written statement that city made several changes to its previous contract offer in hopes of a resolution.

But instead, the changes in the offer drove the union from the bargaining table.

City council last met to discuss the strike strategy on June 25. So did council give the latitude to make the revised offer and management waited 10 days to present it or were the revisions made over the weekend by senior management?

“I would be surprised if council directed senior management to come back with the changes that they are proposing in their last package, but that's a question for them to answer,” Navarroli says.

The mayor and city manager, Art Zuidema, wouldn’t answer that question or any other questions from CTV News about the impasse.

Zuidema speculated in a written statement what may have triggered it.

"The city has heard the union might not understand the city's proposal to use part time and temporary unionized employees to work on Sundays. This offer was made to allow full-time Local 101 staff not to work on Sundays. The city sees this as a potential solution to one of the outstanding issues."

But CUPE is not telling the media what specific changes caused negotiations to collapse.

The union has instead called a special membership meeting on Thursday to explain the offer to the city's 750 inside workers.

“It broke our hearts to see the details contained therein. We are nowhere near reaching an agreement with the response the city has given us,” says Navarroli.