``This has been a difficult round of talks for our union,'' Unifor spokeswoman Denise Hammond said during a media briefing.
``It is proving to be the most challenging among the Detroit Three automakers.''
Unifor president Jerry Dias has said that his top priority in the talks is securing investment in Ford's engine facility in Windsor, Ont.
Hammond said the automaker is refusing to follow the pattern of deals reached in recent weeks with General Motors and Fiat Chrysler without several concessions. Those include the immediate introduction of temporary full-time workers that would receive a lower starting wage and concessions in the workers' long-term health-care plans.
``The proposed offsets are of significant concern for our union,'' Hammond said. ``Our aim is to move forward with a secure future for our members.''
Both Fiat Chrysler and General Motors have agreed to invest $554 million each in their Canadian operations.
The deals struck with the two automakers will also see workers receive a two per cent wage increase this year, another two per cent raise in September 2019 and a $6,000 signing bonus plus lump sum bonuses.
Ford workers at Ontario operations in Bramalea, Oakville and Windsor are prepared to go on strike immediately if a deal cannot be reached by the deadline of Monday at 11:59 p.m. ET, Hammond said.
This could be the first strike by Canadian autoworkers at a Detroit Three automaker since 1996, she added.
A Ford spokeswoman said in an email that the automaker ``will work collaboratively with Unifor to negotiate a globally competitive collective agreement.''
- The Canadian Press
The union representing 6,700 autoworkers at Ford's operations in Canada said Monday prospects for a deal between the two sides remained uncertain, hours before a strike deadline.