General Motors assembly workers picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., October 10, 2019. REUTERS/Bryan Woolston

Frank Lee, a striking UAW auto worker from the General Motors assembly plant in Bowling Green, calls a bill collector from his home in Auburn, Kentucky, U.S., October 1, 2019. Picture taken October 1, 2019. REUTERS/Bryan Woolston

Frank Lee walks the picket line with his son, Isiah, near the General Motors assembly plant, during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., October 1, 2019. Picture taken October 1, 2019. REUTERS/Bryan Woolston

Frank Lee, a striking UAW auto worker, and his son Isiah, shop at a discount grocery store in Bowling Green, Kentucky, U.S., Oct 1, 2019. REUTERS/Bryan Woolston

A striking union auto worker leaves the UAW Local 659 after picking up his strike check outside the General Motors Flint Truck Assembly in Flint, Michigan, U.S., October 9, 2019. REUTERS/Brian Snyder

Kai Spande, manager of the General Motors assembly plant, drives his 2020 Chevrolet Corvette past striking auto workers outside the plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 30, 2019. REUTERS/Bryan Woolston TPX IMAGES OF THE DAY

Democratic U.S. presidential candidate Senator Bernie Sanders stands in the back of a pick-up truck while addressing striking United Auto Workers (UAW) and their supporters on the picket line outside the General Motors Detroit-Hamtramck Assembly plant in Hamtramck, Michigan, U.S. September 25, 2019. REUTERS/Rebecca Cook

Democratic U.S. presidential candidate Senator Bernie Sanders carries a Strike sign with striking United Auto Workers (UAW) in Hamtramck, Michigan, U.S. September 25, 2019. REUTERS/Rebecca Cook TPX IMAGES OF THE DAY

Striking United Auto Worker (UAW) member Steve Donagan carries his daughter Regina while walking the strike line with his wife Marylin in Hamtramck, Michigan, U.S. September 25, 2019. REUTERS/Rebecca Cook

Democratic U.S. presidential candidate Senator Elizabeth Warren attends the picket line with striking General Motors Detroit-Hamtramck Assembly plant workers during the United Auto Workers (UAW) national strike in Hamtramck, Michigan, U.S., September 22, 2019. REUTERS/Rebecca Cook

Striking General Motors Detroit-Hamtramck Assembly plant workers and their supporters walk the picket line during the United Auto Workers (UAW) national strike in Hamtramck, Michigan, U.S., September 22, 2019. REUTERS/Rebecca Cook

The sun rises as General Motors assembly workers and their supporters gather to picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 20, 2019. REUTERS/Bryan Woolston

Charlie Highlanger, 59, a GM employee shouts at passing employees entering the assembly plant as he and General Motors assembly workers picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 20, 2019. REUTERS/Bryan Woolston

General Motors assembly workers and their supporters gather to picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 20, 2019. REUTERS/Bryan Woolston

General Motors assembly workers and their supporters gather to picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 20, 2019. REUTERS/Bryan Woolston

General Motors assembly workers and their supporters gather to picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 20, 2019. REUTERS/Bryan Woolston

GM team leader Natalie Walker, 56, leads chants as General Motors assembly workers and their supporters gather to picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 20, 2019. REUTERS/Bryan Woolston

Striking General Motors assembly workers hold a UAW Local 1112 flag during a rally outside the shuttered Lordstown Assembly plant during the United Auto Workers (UAW) national strike in Lordstown, Ohio, U.S. September 20, 2019. REUTERS/Rebecca Cook

General Motors assembly workers picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 17, 2019. REUTERS/Bryan Woolston

General Motors assembly workers picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 17, 2019. REUTERS/Bryan Woolston

Charlie Highlander screams at an employee reporting for work as General Motors assembly workers picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 17, 2019. REUTERS/Bryan Woolston

Bowling Green Police arrive to open the road as General Motors assembly workers picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 17, 2019. REUTERS/Bryan Woolston

General Motors assembly workers picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 17, 2019. REUTERS/Bryan Woolston

General Motors assembly workers picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 17, 2019. REUTERS/Bryan Woolston

General Motors assembly workers picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 17, 2019. REUTERS/Bryan Woolston

General Motors assembly workers picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 17, 2019. REUTERS/Bryan Woolston

General Motors assembly workers picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 17, 2019. REUTERS/Bryan Woolston

General Motors assembly workers picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 17, 2019. REUTERS/Bryan Woolston

General Motors assembly workers picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 17, 2019. REUTERS/Bryan Woolston TPX IMAGES OF THE DAY

General Motors assembly workers picket outside the General Motors Bowling Green plant during the United Auto Workers (UAW) national strike in Bowling Green, Kentucky, U.S., September 17, 2019. REUTERS/Bryan Woolston

General Motors assembly worker Kandie Deweese pickets outside the General Motors Powertrain Flint Engine plant during the United Auto Workers (UAW) national strike in Flint, Michigan, U.S. September 16, 2019. REUTERS/Rebecca Cook

General Motors assembly workers picket outside the General Motors Detroit-Hamtramck Assembly plant during the United Auto Workers (UAW) national strike in Hamtramck, Michigan, U.S., September 16, 2019. REUTERS/Rebecca Cook

General Motors assembly workers picket outside the General Motors Flint Assembly plant during the United Auto Workers (UAW) national strike in Flint, Michigan, U.S., September 16, 2019. REUTERS/Rebecca Cook

General Motors assembly workers picket outside the General Motors Flint Assembly plant during the United Auto Workers (UAW) national strike in Flint, Michigan, U.S., September 16, 2019. REUTERS/Rebecca Cook

United Auto Worker, Aramark worker Mike Mucci, carries a UAW flag while picketing outside the General Motors Detroit-Hamtramck assembly plant in Detroit, Michigan, U.S. September 15, 2019. REUTERS/Rebecca Cook

Fiat Chrysler Automobiles (FCA) Toledo Jeep plant workers Tom Hall (L), Greg Harmon and Jim Young stand outside the UAW Local 12 union hall in Toledo, Ohio, U.S., March 6, 2019. Picture taken March 6, 2019. REUTERS/Rebecca Cook

Fiat Chrysler Automobiles (FCA) Toledo Jeep plant workers Greg Harmon (L) and Tom Hall stand inside the UAW Local 12 union hall in Toledo, Ohio, U.S., March 6, 2019. Picture taken March 6, 2019. REUTERS/Rebecca Cook

General Motors Chief Executive Officer Mary Barra talks with United Auto Workers union Vice President Terry Dittes and UAW Region 1 Director Frank Stuglin at the GM Orion Assembly Plant in Lake Orion, Michigan, U.S. March 22, 2019. REUTERS/Rebecca Cook

United Auto Workers (UAW) union delegates listen to speakers during the 'Special Convention on Collective Bargaining' in Detroit, Michigan, U.S. March 13, 2019. REUTERS/Rebecca Cook

United Auto Workers (UAW) union delegates chant "we are one" during the 'Special Convention on Collective Bargaining' in Detroit, Michigan, U.S. March 13, 2019. REUTERS/Rebecca Cook

United Auto Workers (UAW) union President Gary Jones addresses the media as UAW Vice-Presidents Cindy Estrada and Terry Dittes listen during the 'Special Convention on Collective Bargaining' in Detroit, Michigan, U.S. March 13, 2019. REUTERS/Rebecca Cook