The movement, which includes the groups Fast Food Forward and Fight for 15, is part of a growing union-backed effort by low-paid workers — including many Walmart workers and workers for federal contractors — that seeks to focus attention on what the groups say are inadequate wages.

The fast-food effort is backed by the Service Employees International Union and is also demanding that restaurants allow workers to unionize without the threat of retaliation.

Officials with the National Restaurant Association have said the one-day strikes are publicity stunts. They warn that increasing pay to $15 an hour when the federal minimum wage is $7.25 would cause restaurants to rely more on automation and hire fewer workers.

Industry officials say that only a small percentage of fast-food jobs pay the minimum wage and that those are largely entry-level jobs for workers under 25.