WASHINGTON—Billy Raye, a 51-year-old unemployed bike courier, is looking for work.

Fortunately for him, the Mid-Atlantic Regional Council of Carpenters is seeking paid demonstrators to march and chant in its current picket line outside the McPherson Building, an office complex here where the council says work is being done with nonunion labor.

"For a lot of our members, it's really difficult to have them come out, either because of parking or something else," explains Vincente Garcia, a union representative who is supervising the picketing.

So instead, the union hires unemployed people at the minimum wage—$8.25 an hour—to walk picket lines. Mr. Raye says he's grateful for the work, even though he's not sure why he's doing it. "I could care less," he says. "I am being paid to march around and sound off."

Protest organizers and advocacy groups are reaping an unexpected benefit from continued high joblessness. With the national unemployment rate currently at 9.5%, an "endless supply" of the out-of-work, as well as retirees seeking extra income, are lining up to be paid demonstrators, says George Eisner, the union's director of organization. Extra feet help the union staff about 150 picket lines in the District of Columbia and Baltimore each day.