The Unifor union and Toyota are already sparring in earnest over the union's attempt to organize the auto maker's two Ontario plants – disputing the number of employees who would belong to the union.

As Unifor applied on Monday to the Ontario Labour Relations Board for certification at Toyota Motor Manufacturing Canada Inc., it contended that the auto maker employs about 6,500 people in Cambridge, Ont., and Woodstock, Ont.

However, Toyota spokesman Greig Mordue disputes that number. "There are significantly more people in the bargaining unit than that," he said.

Story continues below advertisement

The issue of how many employees work at the two plants will be a critical factor as Unifor seeks to make a breakthrough that has eluded other unions – organizing from within an auto plant or plants operated in North America by an Asian or Europe-based auto maker. The union must persuade 50 per cent of employees plus one in the potential bargaining unit to win certification.

Unifor said on Monday that enough workers at the two plants have signed union cards to take the issue to a vote, which the union expects to happen next week.

"We are absolutely confident we have enough cards," Unifor president Jerry Dias said at a news conference in Kitchener, Ont., where he was accompanied by several Toyota workers who were active in the organizing drive.

"This really isn't about wages and benefits," Mr. Dias said. "This is about the Toyota team members saying they want a collective agreement. They want to stop the arbitrary decisions and they want to have a voice in the workplace."

One of few plants operated by a non-North American auto maker that was unionized was a joint venture in California operated by General Motors Co. and Toyota Motor Corp.

But none of Toyota's greenfield plants, or those of its rivals Honda Motor Co. Ltd. and Nissan Motor Co. Ltd., or European auto makers has gone from non-union to union.

So one of the key questions if the union is successful is whether that would affect the competitive position of the Canadian plants and thus lead to Toyota's parent company scaling back investment in Canada.

Story continues below advertisement

"I doubt that would have an effect," said Jeffrey Liker, a University of Michigan professor who watches Japanese auto makers closely and has written books about Toyota. "Toyota's attitude tends to be, we will work with the hand that's dealt us and we'll make the best of it."

The employees who spoke at the news conference pointed to health and safety concerns, the elimination of a defined benefit pension plan for newly hired employees and what they called arbitrary changes in work schedules as reasons for joining Unifor and encouraging their colleagues to do so as well.

Carrie Ann Ostrom, an 11-year Toyota employee who has had surgery on her hands for carpal tunnel syndrome, said the mutual respect between employees and management has deteriorated "I won the lottery, I'm at Toyota, but that comes with a price," Ms. Ostrom said.

Toyota's Mr. Mordue said people who are thinking of joining the union should consider how Unifor will affect the unique values that have helped Toyota grow for 25 years in Canada.

"They have to think hard about what Unifor is selling," he said. "They've talked about improved pensions, they've talked about better pay and benefits, a greater commitment to safety, but the reality is when you already have a package that's at or near the top of the industry, our team members have to question what it is that Unifor is going to negotiate."

Editor's Note: An earlier version of this article incorrectly said the only plant operated by a non-North American auto maker that was unionized was a joint venture in California operated by General Motors Co. and Toyota Motor Corp. In fact, there are other plants operated by non-North American auto makers that are unionized.