Contract talks are expected to resume today between Unifor Local 195 and Flex-N-Gate in Tecumseh.
Over the weekend, the workers at the Howard Division facility rejected a tentative deal.
Local 195 President John Toth says the unionized workers shot down the the deal by a "significant amount."
The 580 workers make auto parts primarily for Ford and FCA.
Toth says the current collective agreement expires on May 17.