In its negotiations with the striking United Auto Workers union, General Motors has put a seemingly tantalizing offer on the table: It has proposed building a new plant in Ohio to produce batteries for some of the one million electric cars it hopes to sell globally by 2026.

The plant would be near the Lordstown factory where G.M. stopped making cars in March. It would create several hundred jobs in the hard-hit region, and give the union a foothold in the industry’s coming transition to electric vehicles.

But in other ways, the offer illustrates the technological and economic shifts that have left manufacturing workers across the United States worrying that their living standards and their prospects are in decline.

According to people familiar with the outlines of the offer, the plant would probably pay about $17 an hour, well below the $31 an hour that many assembly workers earned in Lordstown. The operation would be under a separate contract. And the work force would be far smaller than the more than 3,000 who once assembled the Chevrolet Cruze there.