AT&T workers in Maine walked off their jobs Friday and will picket at nine company retail stores in Maine through Sunday.

About 21,000 workers represented by the Communications Workers of America went on a three-day strike beginning Friday to protest AT&T’s contract proposals. In Maine, 65 workers at nine AT&T retail stores are on strike and will picket outside some of the stores this weekend, said Serina DeWolfe, president of the CWA Local 1400, representing workers in Maine, New Hampshire and Vermont.

DeWolfe said she expects that some stores will remain open, but she doesn’t know who will be working in them. She asked that customers “be mindful of the workers” and respect the picket lines by waiting to visit stores for problems or new phones until Monday. DeWolfe said the stores affected by the strike are in Bangor, Ellsworth, Brunswick, Auburn, Saco, Scarborough, Windham, at the Maine Mall in South Portland, and on Marginal Way in Portland.

DeWolfe said the key issues for workers include an incentive pay structure that has been “greatly diminished” over the past several years, significantly lowering the overall compensation for store workers. Though only retail store workers are involved in the strike in Maine, technicians and call center workers will be part of the three-day strike in California, Nevada and Connecticut.

AT&T said Friday it is offering terms that will make employees “better off financially” and that the strike involves less than 14 percent of workers. “We’re prepared, and we will continue working hard to serve our customers,” the statement said