Market Basket employees are organizing to defend themselves on their own behalf for the first time after Gov. Deval Patrick joined company management in calling for workers to return to their jobs as negotiations for a sale continue.

This is a first. To date, employee efforts have focused on restoring Arthur T. Demoulas as CEO. But Patrick’s call — echoing current management for workers to return to their jobs — seems to have changed all that.

The protesting Market Basket employees gathered across the street from the company’s Tewksbury headquarters say most of them now have received Fed Ex-ed letters from the CEOs. One batch sent to office workers said to return to work by Friday or their jobs would be considered abandoned. Another set of letters sent to warehouse workers and truck drivers said they had to return by Monday — or else risk being replaced.

“The letters that they received had said that they had received multiple notices," said former operations manager David McLean. "This is the first letter that any of them received.”

McLean says the CEOs had not given workers any previous direct notice. So now, employees are sending a letter back.

'It's easy for him to say everybody go back to work. He doesn't understand what's going on. Obviously, we're not listening to what he says. He doesn't control us. We control ourselves. Nobody's forcing us to stay here.'

"The correspondence going back to them is stating that fact, and stating that they have not abandoned their jobs, that because of the hostile environment and threatening management that exists over at the corporate office, they are collectively and as a group banding together to protect the company that they knew,” he said.

The key words there were “hostile environment.” A lot of the employees were suddenly using those words. And those are fighting words in the legal world, says employment attorney Catherine Reuben.

"It is a word that people like to bandy around because it’s a word that suggests something unlawful is going on here," Reuben said. "That can give rise to claims under both Massachusetts state and federal law, and you can bring claims before the Massachusetts commission against discrimination or equal employment opportunity commission."

Whether, in this case, that argument would work is still an open question. But employees are saying they’ve also contacted the National Labor Relations Board to file a formal complaint against company management for creating a threatening workspace.

That’s a big change — until now many have insisted that they only need to maintain faith in Arthur T. Demoulas and support a boycott of Market Basket stores.

But everyone’s getting on board. One of the protesting employees read the letter aloud to about a hundred workers before laying it down on a table for everyone to sign.

“So sign up, it’s a good thing, it’s all for us, sign it," the employee said. "Don’t ask questions, it’s for the love of our company … ”

People quickly lined up to add their signatures. Patrick’s terse statement Wednesday urging workers to return to their jobs seems to have sparked their change in attitude. Market Basket employee Rosie Hagopian says everyone feels threatened.

"It’s easy for him to say everybody go back to work," Hagopian said. "He doesn’t understand what’s going on. Obviously, we’re not listening to what he says. He doesn’t control us. We control ourselves. Nobody’s forcing us to stay here."

But Hagopian admits: "Some of us are scared. Definitely scared. But we know we’re going to get back to normal."

Paul St. Jean, who managed the Market Basket warehouse in Lawrence, is comforted by this thought: “How can they replace 700 people? How can they get the company going again with 700 new people? It just can’t be done."

St. Jean says the only option that remains for employees or management is to come an agreement.