DETROIT—General Motors CEO Mary Barra joined negotiators at the bargaining table, an indication that a deal may be near to end a monthlong strike by members of the United Auto Workers union that has paralyzed the company’s factories.

Barra and GM President Mark Reuss were in the bargaining room early on Oct. 15, but they left later in the morning as committees began work on specific contract language. The appearance of two key executives is a strong sign that bargainers are closing in on a contract agreement that would end the strike.

About 49,000 UAW members walked off their jobs Sept. 16 after their four-year contract expired. The strike has shut down all of GM’s U.S. factories and hampered production in Canada and Mexico.

The only issues that remain to be settled are faster pay increases for workers hired after 2007, apprenticeships for skilled trades workers, and the specifics of winding down a joint union-company training center.

Both sides are under pressure to end the walkout, which has cost GM close to $2 billion in profits and forced workers to live on $250 per week, about one fifth of their base pay. Last week, with the strike dragging on, the union said it would increase strike pay to $275 per week.

The union has summoned its national council of factory-level leaders to Detroit for a meeting Thursday that was billed as an update on contract talks. The group could be assembling to vote on a tentative agreement. It also will decide if workers should return to their jobs before or after they vote on the deal.

The strike, now in its 31st day, is the longest against an automaker since a 54-day strike in 1998.

A union demand that all vehicles sold in the U.S. be built here apparently has been resolved, but the terms are unknown. The company did offer $9 billion worth of investments at U.S. factories, $7.7 billion from the company and another $1.3 billion from joint ventures. The $1.3 billion includes a battery cell factory in the area of Lordstown, OH, where GM wants to close an assembly plant.