(USA TODAY) -- In Washington, D.C., dozens of people carried signs and marched whilesinging "Jingle bells, jingle bells, jingle all the way, it's no fun,to survive, on low low low low pay."

In New York City, about 100protesters blew whistles and beat drums as they marched into aMcDonald's chanting "We can't survive on $7.25."

And in Detroit,more than 100 workers picketed outside two McDonald's restaurants,singing "Hey hey, ho ho, $7.40 has got to go!"

One-day laborwalkouts were planned at fast-food restaurants in 100 cities Thursday,with protests in scores more cities and towns across the nation.Organizers, actually a loose-knit group of labor advocates mostly led bythe Service Employees International Union, are pressing for an increasein the federal minimum wage, higher wages in the industry, and theright to unionize without management reprisals.

The advocacygroups are hoping to build public support for raising the federalminimum wage of $7.25, or about $15,000 a year for full-time work. Acommon battle cry has been "Fight for 15" - a $15-per-hour minimum wage.

TyeishaBatts, 27, protesting in New York, said she has been working at BurgerKing for about seven months and earns $7.25 an hour. She said she hasn'tbeen retaliated against but said her manager warned that employees whodidn't arrive on time Thursday would be turned away from their shifts.

"My boss took me off the schedule because she knows I'm participating," Batts said.

InDetroit, the Rev. Charles Williams II, president of National ActionNetwork, thanked protesters for their support and encouraged fast-foodcustomers to aid the effort.

"We need them to sacrifice with us,"he said. "We are sacrificing our time, the workers are sacrificing theirwages. We need people who eat fast food to sacrifice their coffee, tosacrifice their McMuffin."

Arun Gupta, an advocate for income equality and founding editor of the Occupy Wall Street Journal, says he is encouraged by the nationwide effort but isn't expecting major changes.

"It's more a show for the media than something that will hit the bottom line of these employers," Gupta said.

The timing is good. In recent days, Pope Francis and President Obama have spoken out against growing income inequality.

"Howcan it be that it is not a news item when an elderly homeless persondies of exposure, but it is news when the stock market loses twopoints?" the pope asked.

Obama, who has expressed support for aDemocratic proposal to raise the minimum wage to $10.10 per hour, echoedthe pope's concerns in a speech Wednesday. Obama noted that theAmerican economy had doubled in size since 1979, but most of that growthhas been restricted to a "fortunate few."

Despite the growingconcern surrounding economic disparities, the pushback is strong. Fastfood is a price-sensitive business - and the industry claims it would bedifficult to significantly increase wages.

"Fifteen dollars anhour is not a reasonable approach," said Justin Winslow, the MichiganRestaurant Association's vice president of government affairs. Inaddition, the industry counters that many fast-food workers are youngerworkers seeking part-time work, not necessarily a lifetime career in theindustry.

The National Restaurant Association, an industrylobbying group, said most of Thursday's protesters were union membersand that "relatively few" workers have participated in past actions. Itcalled the demonstrations a "campaign engineered by national laborgroups."

Fast-food workers have historically been seen asdifficult to unionize, given the industry's high turnover rates. But theService Employees International Union, which represents more than 2million workers in health care, janitorial and other industries, hasbeen providing considerable organizational and financial support to thepush for higher pay over the past year.

Supporters of wage hikeshave been more successful at the state and local level. California,Connecticut and Rhode Island raised their minimum wages this year. Lastmonth, voters in New Jersey approved a hike in the minimum to $8.25 anhour, up from $7.25 an hour, and the city of SeaTac, Wash., approved aminimum wage of $15 per hour.

Labor Secretary Tom Perez weighed inon the side of the protesters this week in his blog: "To reward work,to grow the middle class and strengthen the economy, to give millions ofAmericans the respect they deserve - it's time to raise the minimumwage."

Contributing: Detroit Free Press staff; Associated Press