U.S. fast-food customers in search of burgers on Thursday might run into striking workers instead.

Fast-food workers protested in U.S. cities including New York, Chicago and Detroit, with organizers expecting the biggest national walkouts yet in a demand for higher wages.

Organizers say thousands of fast-food workers were set to stage walkouts in about 50 cities, part of a push to get chains such as McDonald's, Taco Bell and Wendy's to pay wages that people can live on. The restaurants were to stay open.

Workers say they want $15 US an hour, which would be about $31,000 US a year for full-time employees. That's more than double the federal minimum wage, which many fast food workers make, of $7.25 an hour, or $15,000 a year.

White House urges higher minimum wage

The move comes amid calls from the White House, some members of Congress and economists to raise the minimum wage, which was last raised in 2009. But most proposals seek a far more modest increase than the one workers want. President Barack Obama wants to raise it to $9 an hour.

The push has brought considerable attention to the so-called "McJobs" that are known for their low pay and limited prospects.

Fast-food workers say they can't live on what they're paid.

Shaniqua Davis, 20, lives in New York City with her boyfriend, who is unemployed, and their one-year-old daughter. Davis works at a McDonald's, earning $7.25 an hour. Her schedule varies, but she never gets close to 40 hours a week. "Forty? Never. They refuse to let you get to that (many) hours."

Her weekly paycheque is $150 or much lower. Davis plans to take part in the strike Thursday.

McDonald's, Burger King respond

McDonald's Corp. and Burger King Worldwide Inc. say they don't make decisions about pay for the independent franchisees that operate the majority of their U.S. restaurants.

For the restaurants it does own, McDonald's said in a statement that pay starts at minimum wage but the range goes higher, depending on the employee's position and experience level. It said that raising entry-level wages would mean higher overall costs, which could result in higher prices on menus.

"That would potentially have a negative impact on employment and business growth in our restaurants, as well as value for our customers," the company said in a statement.

The Wendy's Co. and Yum Brands Inc., which owns KFC, Pizza Hut and Taco Bell, did not respond to a request for comment.

The National Restaurant Association says the low wages reflect the fact that most fast-food workers tend to be younger and have little work experience. Scott DeFife, a spokesman for the group, says that doubling wages would hurt job creation, noting that fast-food chains are already facing higher costs for ingredients, as well as new regulations that will require them to pay more in health care costs.

Mary Kay Henry, president of the Service Employees International Union, which is providing the fast-food strikes with financial support and training, said the actions in recent months show that fast-food workers can be mobilized, despite the industry's relatively higher turnover rates and younger age.

"The reality has totally blown through the obstacles," she said.