"Talks are not moving at a pace we'd like to see," Jerry Dias said. "But we're still talking."
A strike deadline is set for 2 p.m. Monday when as many as 900 union members could walk out.
Dias said Bombardier is asking for "major concessions" including the elimination of post-retirement benefits to workers with less than 5 years experience. Dias said that's about 70 per cent of the workforce at the Thunder Bay plant.
"It's not something we're willing to entertain," he said.
The other serious concern for Unifor is the amount of work being sent to Mexico, Dias said, noting that all of the public transit vehicles built in Thunder Bay, are used in Ontario.
"This is product that is paid for by Ontario taxpayers", he said. "There's no question about it. This is our work and it should be creating jobs in Canada."
A Bombardier spokesman says the company is determined to reach a deal where it remains competitive and can help it to bring more work to Thunder Bay.
There was a brief strike in 2011 over similar issues and Dias says Bombardier should be under no illusions about the workers' determination.
There was no "significant" progress between the two sides as of Sunday evening, Dias said.
"We've had a lot of discussions, he said. "But we seem to be stuck in the mud, but hopefully things will change as we get a little closer to the (strike) deadline."
The Thunder Bay facility makes rail and mass transit cars for cities, including Toronto's subway system.