Even as General Motors Co. and the United Auto Workers union come closer to resolving their biggest work confrontation in decades, a larger, unsettled issue is the inevitable pain for U.S. workers from GM’s long-range bet on electric cars.

GM’s need to free up cash to invest in electrics has led it to make deep cuts in its core business, including its decision to close four U.S. factories —a main point of friction in the longest walkout at GM since 1970.

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