General Motors has temporarily enlisted salaried volunteers to build midsize pickups at its plant in Wentzville, Mo., until absenteeism improves or enough temporary workers and transfers arrive.

But the UAW strongly objects to GM’s move, claiming that appointing salaried employees, rather than hourly UAW members, breaches the GM-UAW labor contract.

“We have strenuously objected to this violation of the contract,” said UAW spokesman Brian Rothenberg. “The local union has started the grievance process.”

GM spokesman Jim Cain said the number of salaried workers on the line in Wentzville varies by week. Some weeks the total has exceeded two dozen, he said.

Coronavirus cases continue to climb in Missouri. The state has reported 35,563 new cases in the last month, according to Johns Hopkins.

Unless absenteeism improves, Cain said GM likely will need the volunteers until UAW workers can transfer to Wentzville from other plants and GM can hire more temporary workers. The Detroit Free Press first reported that salaried employees were working in Wentzville.

The plant typically employs 4,100 salaried and hourly workers. It builds the Chevrolet Colorado and GMC Canyon midsize pickups, along with the Chevy Express and GMC Savana full-size commercial vans. The automaker has local ads running in an attempt to hire about 200 temps.

In late July, GM reversed a plan to temporarily cut the third shift at the plant, after confirming the elimination of the shift because of worker absenteeism less than three weeks earlier.

GM told Automotive News at the time that there was enough demand for three shifts. The automaker was working on a staffing plan to resume a three-shift schedule as soon as possible.

“We have been able to maintain three shifts to meet customer and dealer demand, so the impact on our inventory rebuild should be negligible,” Cain said Tuesday. “We’re grateful for the support we have received as the plant works through a very difficult staffing challenge.”