Last month, a dozen workers walked through Philadelphia International Airport just before 5 a.m., wondering whether they still had jobs. The repercussions of their walkout the day before - a protest over pay and conditions - would be seen when they tried to clock in.

Standing among the anxious group were three members of City Council.

The pre-dawn escort was only the latest wage-equality crusade to draw Council's attention.

Some want Council's next step to be radical - passing a $15 citywide minimum wage, despite state law that seems to say it can't.

The city solicitor is studying whether such an effort, sure to lead to a court battle, would be plausible. If it is, Councilman Kenyatta Johnson said he would strongly consider introducing minimum-wage legislation.

"I want to make sure that as a part of this process we don't hurt small businesses," Johnson said. "But, nevertheless, there are major corporations that could sustain such a wage increase."

The heightened focus on raising wages here, which some critics dismiss as an election-year gimmick, comes as President Obama pushes to raise the federal minimum wage to $10.10 from $7.25, set in 2009. The effort has won over many Democrats, and even some Republican leaders have recently backed increases in their home states, especially if voter support is high.

Where efforts to raise the state rate have failed, pushes for a city rate have become more common, according to Tsedeye Gebreselassie, a lawyer for the National Employment Law Project.

Nearly two dozen cities and counties have instituted minimum wages, including Seattle, which in June passed a $15 minimum wage - the highest nationwide - to be phased in by 2021. Proposals are under consideration in Los Angeles, Chicago, and New York.

Half a dozen bills to raise Pennsylvania's minimum wage, which is the same as the federal rate, died in the Republican-led statehouse this year.

If Philadelphia wants to go it alone, one major legal snag stands in the way.

A 2006 preemption clause added to the state's 1968 wage act - which says the law trumps local ordinances on the topic - has long been read as banning cities from setting their own rates.

A local group, 15Now Philly, says otherwise.

It argues that the intent of the state law was to protect workers from low pay. The preemption, read with that intent in mind, is unclear on whether it bans municipalities from going above, or only below, the state wage, it says.

It's an intriguing argument to Mark Aronchick, a former Philadelphia city solicitor who said he often pushed the boundaries of city control in the 1980s.

"I would be persuaded that I had to look at this very carefully," he said after reading 15Now's memo. "It's worthy of serious study."

Aronchick, a University of Pennsylvania professor who has taught on city minimum wages, says the preemption is "strong but not conclusive."

Few Council members have publicly weighed in. But it and Mayor Nutter have shown a clear interest in wage issues in recent months.

In June, Nutter signed an executive order setting the minimum wage for city contract workers at $10.88. In October, Council approved a tax break for companies that pay $12 an hour. At a recent Council hearing, several members gave impassioned speeches about paying airport employees more.

Nutter's spokesman, Mark McDonald, said 15Now had not sought the mayor's support for its effort. Nutter signed a letter in October urging Congress to raise the federal minimum wage.

Councilman Jim Kenney, who asked the Solicitor's Office to review 15Now's argument, said through his staff he hadn't decided whether to support the measure.

Councilman Ed Neilson, who joined the airport workers after their walkout, along with Johnson and Councilwoman Maria Quiñones-Sánchez, said he supported raising the minimum wage but was hesitant to draw the city into a legal battle.

"I'm not willing to spend the city's resources on lawsuits when I can spend it on kids' education," said Neilson, a former labor leader and state representative who introduced a minimum-wage bill this year in Harrisburg.

David W. Patti, president and CEO of the Pennsylvania Business Council, warned that raising wages would cause businesses to migrate across the county line. "If you want to attract people to your region, we generally look at trying to reduce the cost of doing business," he said.

He also questioned whether Council's interest in the topic was genuine, calling it a product of the coming election cycle. All 17 Council seats are up for grabs next year, as is the Mayor's Office.

John Dodds, director of the Philadelphia Unemployment Project and a longtime advocate for raising wages, said Council was more likely responding to the groundswell of activism on the issue throughout the country.

He called the $15 goal lofty, noting that Nutter had twice vetoed bills that would have given workers three mandatory sick days. (A task force studying sick leave will release its report Monday.) But he said the promise of $15 an hour might grab enough attention to gain traction.

"People might say it's not going to happen," Dodds said. "But at least we can get $10 or $11."

The airport workers who walked off the job in November will see their pay jump to $12 in July under Nutter's executive order. They have been pressing their company, airline contractor PrimeFlight, to comply sooner.

At the airport the day after their work stoppage, as each employee's ID was accepted, the group's tension eased.

The Council members among them gave out hugs and handshakes as the workers left to begin their shift.