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By Mary Wisniewski
CHICAGO, May 15 (Reuters) - U.S. fast-food workers seeking higher wages are planning a strike on Thursday that could affect thousands of restaurants that they say make huge profits from paying them a pittance.
The strike will be the latest in a series of protests over the past 18 months in the United States that have targeted fast-food restaurant operators, including McDonald's Corp and Burger King Worldwide Inc.
They come at a time when U.S. Democrats have been mounting efforts to raise the federal minimum wage ahead of this year's mid-term congressional elections, seeing income inequality as a powerful campaign issue.
Fast-food workers are seeking $15 an hour and the right to unionize without retaliation, union leaders said.
McDonald's, the world's biggest restaurant chain by revenue, and Burger King have defended their treatment of employees, saying they pay fare wages.
Jessica Davis, 25, a single mother of two who earns $8.98 an hour as a crew trainer at a Chicago McDonald's restaurant, said she needs more to make ends meet.
"I'm tired of making so much money for this company and they can't give me a decent wage and decent hours," said Davis, who has four years on the job but relies on family and public assistance. "I don't think we should have to live this way."
The strike will be in 150 cities including Boston, Chicago, New York, Philadelphia and Miami.
President Barack Obama has pushed Congress to raise the federal minimum wage to $10.10 per hour from the current $7.25, a move fought by the Republicans in Congress.
Twenty-one states and Washington, D.C. have minimum wages higher than the federal minimum wage, and 38 states have considered minimum wage bills during the 2014 session, according to the National Conference of State Legislatures. The state of Washington has the highest minimum wage, at $9.32 an hour.
(Reporting by Mary Wisniewski; Editing by Jon Herskovitz and Steve Orlofsky)