United Auto Workers President Shawn Fain on Sunday called for a strike at a Michigan factory that makes axles for GM pickup trucks.
Workers at the Dauch Corp plant in Three Rivers will walk off the job at midnight (0400 GMT). About 1,000 unionized workers are employed there.
GM said it is closely monitoring the situation and assessing any potential impact.
The union demands wage increases after workers took pay cuts in 2008 to keep the plant open. Top pay is now $22 per hour, down from $29 in 2008.
