DETROIT (AP) — If U.S. consumers ever ditch fuel burners for electric vehicles, then the United Auto Workers union is in trouble.

Gone would be thousands of jobs at engine and transmission plants across the industrial Midwest, replaced by smaller workforces at mostly automated factories that mix up chemicals to make batteries.

The union is aware of this possibility as it negotiates for the future as much as the present in contract talks with General Motors. Meanwhile, more than 49,000 union workers are on strike against the company and have shut down its factories for the past six days.

GM CEO Mary Barra has promised an "all-electric future," with the company going through a painful restructuring to raise cash in part to develop 20 electric models that it plans to sell worldwide by 2023.