Market Basket managers have reaffirmed their commitment to working for nobody else but fired CEO Arthur T. Demoulas, saying they’ll quit if he isn’t reinstated — a threat that could remove the working management of most of the chain’s stores, already reeling from a loss of customers and protests by thousands of workers.

Managers and assistant managers from 68 of the Tewksbury chain’s 71 stores had signed a petition by yesterday evening stating they would resign immediately if Demoulas isn’t reinstated “with full authority” or another buyer other than Demoulas purchases the company, according to Steve Paulenka, a former Market Basket facilities and operations supervisor who was fired July 20 for helping spearhead employee protests and job walk-offs.

Workers planned to deliver the petitions to board members and the company’s new co-CEOs yesterday. Paulenka expected to have the signatures of all managers — including individual department managers — from all 71 stores in hand by today.

The board met via a conference call last night, several sources said, but no action was immediately announced on offers to buy the chain. Board president Keith Cowan declined comment.

Demoulas last week offered to buy the 50.5 percent of the grocery chain that’s owned by family members aligned with his rival cousin, Arthur S. Demoulas, who last year gained control of the Market Basket board that ousted the former CEO last month. That undisclosed offer still is under consideration by Market Basket’s board and shareholders.

Market Basket employees yesterday continued their protests outside stores and the company’s Tewksbury headquarters and warehouse for a second week in their effort to shut down the chain’s operations and pressure the board to rehire Arthur T. Demoulas.

“There’s still people going to work because we want them to get paid,” Paulenka said of store workers. “But there’s nothing for them to do. There’s vast numbers of people going out to man the (protest) lines. The customers are still staying away.”

The company’s board and new co-CEOs Felicia Thornton and James Gooch have been calling for employees to return to work in the past week. The co-CEOs on Friday pledged that those who resumed working would not be penalized or disciplined.