GM talks already started
Contract talks have opened between Unifor and both Ford and Fiat Chrysler.
"We have one simple message for all the Detroit Three automakers: there can be no deals without commitments to new investments in Canada," Unifor president Jerry Dias said. "Our workers are the most highly skilled and productive in the world."
Talks with General Motors formally began on Wednesday.
Discussions are expected to happen until after Labour Day, when one company is selected to set the pattern for bargaining.
In this round, Unifor said it will also look to auto companies to join it in advancing pharmacare.