For now, he said, they're working on union-related issues and organizing rallies. But their ultimate goal is to coalesce around one labor-backed candidate in 2015.
"It's a thinktank that turns into a 'do tank,' " Dougherty said. "It's not a matter of if we're going to be all together, it's a matter of who we're going to be all together behind."
If the labor coalition stays united, its chosen candidate will be formidable.
City campaign-finance rules limit contributions from a single political-action committee to $11,500 per calendar year, preventing one moneyed group from bankrolling a campaign. But the unions control dozens of PACs and would be able to give their candidate a formidable war chest. Many also run their own get-out-the-vote organizations.
So, who will be the lucky candidate? Dougherty said that, so far, there has been no discussion about specific candidates. But many sources say the favorite would be Council President Darrell Clarke - if he decides to run.
"Darrell Clarke is the leading candidate to date, followed by [City Controller Alan] Butkovitz," said Henry Nicholas, president of the National Union of Hospital and Health Care Employees' District 1199C.
Clarke and Butkovitz have talked with the group about labor issues - but not about the mayor's race, Dougherty said.
Asked about running, Clarke said he's "just focused on being the best Council president I can be right now." Butkovitz said he believes that, if he runs, he could get the backing of the labor community.
Nicholas added that while other potential candidates could get the coalition's support - Councilman Jim Kenney or former District Attorney Lynne Abraham - there's one who likely can't: state Sen. Anthony Williams, whose support for school vouchers would make him a nonstarter for the teachers union and its allies.
Williams said he is trying to build support across the "widest band of Philadelphia," not just unions. He said the coalition's endorsement may not be a golden ticket to the Mayor's Office.
"Just as [voters] talk about my donors, people will follow who labor supports and they'll decide whether they're comfortable with that," said Williams, whose 2010 gubernatorial campaign was scrutinized for several large donations he received from school-voucher advocates.
While Williams might not get widespread labor backing, he is rumored to have the support of another formidable force in local politics: U.S. Rep. Bob Brady, the city Democratic Party chairman who ran in the 2007 primary.
Brady, a former union carpenter, so far has kept mum about potential candidates but said he thinks labor unity is a "great idea."
"I wish they were together when I was running," Brady said. "I'd have been the mayor."
The monthly meetings are a who's who of labor in Philadelphia. Dougherty said attendees have included: Pete Matthews, of the blue-collar municipal union; Fred Wright, of its white-collar counterpart; Jerry Jordan, of the Philadelphia Federation of Teachers; Joe Schulle, of the firefighters union; Ryan Boyers, of the laborers; Pat Gillespie, of the Building & Construction Trades Council; Pat Eiding, of Pennsylvania AFL-CIO; and others.
Notable absences include Ed Coryell, of the carpenters, and John McNesby, of the Fraternal Order of Police Lodge 5. (Dougherty said he keeps McNesby advised of the group's doings.)
The group lunches on a different Philly favorite each meeting, Dougherty said, including Tommy DiNic's in Reading Terminal, the Famous 4th Street Deli in Queen Village and Joe's Pizza on 16th Street.
The meetings began when local union leaders gathered in summer 2012 to plan the Workers Stand for America rally, which drew tens of thousands of labor activists from across the country to the Ben Franklin Parkway.
They have since planned rallies for other labor causes, like sending a caravan of protesters to Harrisburg when anti-union "paycheck protection" legislation was introduced.
"We had 24 buses full on Delaware Avenue at 6:30 a.m. . . . in a minus-8 windchill factor," Dougherty said. "We filled 24 buses overnight. That's why I'm feeling really good about this."
Matthews, whose blue-collar union has been locked in a five-year standoff with Nutter over contract terms, said he believes the group will stay together in 2015 as a reaction to the mayor's policies.
"It's ironic: He's been the greatest labor unifier we've ever had," said Matthews, president of the American Federation of State, County and Municipal Employees' District Council 33.
As mayor, Nutter has sought less costly pension and health-care benefits, changes in overtime rules and the right to furlough workers. As a result, he's been battling three of the city's four big unions for most of his time in office.
This week, he reached an agreement with AFSCME District Council 47, the white-collar union, ending five years of negotiations.
The situation looks less promising for DC 33. Nutter last year asked the state Supreme Court for permission to impose a contract. Although it was sent down to Common Pleas Court and could take years to resolve, the case rallied unions across the state to Matthews' side.
Matthews often calls Nutter "the Scott Walker of the East," referring to the Republican governor of Wisconsin whose policies sparked massive union protests in 2011.
In a January interview on contract negotiations, Nutter said unions "have a voice and they have a role" but that their voice shouldn't go unchecked.
"There are a million-and-a-half people in this city and growing. I have to represent the union members' interests and the public," he said. "My job is to balance those interests."
Whoever wins the coalition's support will likely have to oppose Nutter's labor policies and promise to sign new contracts as soon as possible.
Sam Katz, the three-time GOP mayoral candidate who recently resigned as chairman of the city's fiscal oversight board, said it was important for Nutter to achieve his benefit reforms before his term ends.
"In the next election, these unions, which clearly have been solidified now . . . will probably try to work together to get the next mayor elected," said Katz, who ran twice against former Mayor John Street and is said to be considering a 2015 run as an independent or Republican candidate.
Dougherty is confident that labor will come out on top in 2015, no matter the opposition.
"Only half this group was together for John Street, and we won," he said.
On Twitter: @SeanWalshDN