(Adds quote from Chicago restaurant patron, Miami demonstrator)
By Mary Wisniewski
CHICAGO, May 15 (Reuters) - U.S. fast-food workers went on strike on Thursday, aiming to convince thousands of restaurants they make huge profits from paying them a pittance and that they deserve a raise.
The one-day strike is the latest in a series of U.S. protests over the past 18 months 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 pushing 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 wages of $15 an hour and the right to unionize without retaliation, union leaders said.
Tammy Castellanos, 35, was among about 200 people who demonstrated Thursday in a cold rain at the Rock & Roll McDonald's near downtown Chicago, which is known for its pop memorabilia.
"I have done so much for Burger King and I don't make enough to pay the rent," said Castellanos, a single mother with five children ranging in age from 21 months to 18 years old. She said she makes $10 an hour after a decade working at Burger King.
Wendy Gonzales, 25, said she makes $8.60 an hour after four years at a McDonald's and lives with her parents in Chicago.
"I am trying to get a raise so I can get my own apartment and be independent," Gonzales said. "I want to go back to school."
Marco Mejia, 66, a Chicago retiree who was eating breakfast at McDonald's, said he supported the workers.
"It's a shame," Mejia said. "The CEOs of these companies are making millions of dollars and do absolutely nothing, and these people are working so hard and make the minimum (wage)."
McDonald's, the world's biggest restaurant chain by revenue, and Burger King have defended their treatment of employees, saying they pay fair wages.
Strikes were expected to be held in 150 cities, including Boston, Chicago, New York, Philadelphia and Miami, where about 50 people gathered in the rain outside of a McDonald's near a downtown hospital.
Among the Miami demonstrators was Selmira Wilson, who said through a translator that it was nearly impossible to care for her three children with the low wages she earned from McDonald's.
"I have to work two jobs," Wilson said. "I clean offices at night just to get by."
U.S. 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 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 in Chicago and Zachary Fagenson in Miami; Editing by Jon Herskovitz, Steve Orlofsky and Jeffrey Benkoe)