It already may be out of their hands.
With the May 19 Democratic primary a month away, the six mayoral candidates are increasingly being reduced to spectators by the volume of television ads produced by organizations officially unconnected to their campaigns.
While they continue to debate, produce policy papers, and skewer one another's positions, none so far appear to have the resources to match the level of ads created by three independent groups in the race at the moment.
One of those groups, American Cities, has thus far spent in excess of $1.9 million to promote State Sen. Anthony H. Williams, according to a political consultant who is unconnected to the campaign but who is tracking ad buys. The group could wind up spending as much as $4 million - or possibly more than all the candidates combined.
Two other groups, known as Building a Better Pennsylvania and Forward Philadelphia, are spending at roughly half that rate to promote Jim Kenney. Their ad buys total about $900,000 thus far, the consultant said.
These groups stand apart in that they are held to less stringent campaign-finance limits than the candidates. That means they can take unlimited money from donors, who can remain anonymous until May 8, the last finance reporting deadline before the primary.
"This is breaking new ground," said David Thornburgh, who heads the watchdog organization Committee of Seventy. "We are all trying to determine what this means and how voters should interpret this, the good, bad, and the ugly."
Mayor Nutter, who made campaign-finance reform a hallmark of his City Council career, is particularly troubled by the opaque nature of the funding for the independent groups now wielding influence over the contest to choose of his successor.
"The general public has no idea how much money these groups actually have, where it came from, and who all is involved," he told The Inquirer. "This has the potential for being the most hidden campaign fund-raising effort in Philadelphia history."
He is right to an extent. There is, however, a general sense of who is funding the current independent efforts. Not known is the scope of that funding.
American Cities, for instance, is a political action committee created largely as a vehicle for money from three Main Line financial traders - Joel Greenberg, Arthur Dantchik, and Jeffrey Yass - who have made school choice a mission. To that end, they backed Williams' unsuccessful 2010 run for governor with $5 million.
Building a Better Pennsylvania was created last year and is funded primarily by Democratic power broker John Dougherty's union, Local 98 of the International Brotherhood of Electrical Workers. It is credited with helping elect U.S. Rep. Brendan Boyle last year and has thrown its weight behind Kenney for mayor.
Kenney is backed by a second independent group, Forward Philadelphia, which is funded by progressives, LGBT activists, and labor unions, including the American Federation of Teachers.
Such PACs are a natural outgrowth of the Supreme Court's 2010 ruling in Citizens United, which declared spending by independent groups a form of protected speech, meaning it cannot be regulated.
There are no limits on donations to such groups.
Given Philadelphia's strict contribution limits - $2,900 for individuals, $11,500 for organizations - it is no surprise unions and wealthy donors with pet causes have turned to independent groups.
The hook is that they cannot coordinate their efforts with candidates they support. That means no communication between the various independent expenditure groups and campaigns.
Barry Kauffman, executive director of Common Cause Pennsylvania, was skeptical.
"I rather suspect that at some point people from the independent expenditure might just happen to show up at the same bar as the candidate's people and information may be exchanged," he said. "It is one of the huge flaws in the Supreme Court's logic to think that these things are ever going to be completely independent."
J. Shane Creamer Jr., executive director of the city's Board of Ethics, acknowledged it was a more difficult standard to police.
"It requires a different level of proof than we are ordinarily dealing with," he said. "It does not make it impossible to prove, but it requires a different type of evidence."
The independent expenditure groups and candidates are adamant they are playing by the rules.
Kevin Vaughan, chairman of Forward Philadelphia, said he hadn't spoken to Kenney since November. "I don't even have any connection one way or the other with the campaign," he said.
Mark L. Alderman, outside counsel for American Cities, said he and others connected to the effort had been meticulous in steering clear of Williams' campaign.
"We have stayed as far away from the coordination line as possible," Alderman said. "We have not had any contact with anyone associated with the campaign."
If the donors to the outside groups are obscure, some names publicly connected with them aren't. Vaughan is a former Democratic ward leader who once headed the city Human Relations Commission. Dougherty has turned Local 98 and its PAC into a political power center. Alderman, a longtime Democratic fund-raiser, helped finance Mayor John F. Street's races.
That was before the caps.
City Councilman W. Wilson Goode Jr., who a decade ago sponsored the legislation that capped campaign contributions in Philadelphia, remains sanguine about the impact of independent spending.
"While I am the author of campaign-finance reform, I have always understood people have rights," Goode said. "And one is to participate in democracy. This is actually a way for more people to have a voice. You don't have to have $1 million to create an independent expenditure. Someone can do it with $1,000 or $100."
But Lynne M. Abraham, running for mayor without the benefit of any any independent groups, was dismissive when asked on the campaign trail whether she thought the law's non-coordination rule would be followed.
Abraham, who was district attorney for 19 years, said Thursday: "My position is: Huh, does anybody really believe that in a place like Philadelphia?"
The amount spent on TV ads for State Sen. Anthony H. Williams by American Cities. The independent group is largely funded by three Main Line financial traders who have made school choice a mission.
The amount spent on TV ads for former City Councilman Jim Kenney by two groups: Building a Better Pennsylvania, funded primarily by Democratic power broker John Dougherty's union of electrical workers, and Forward Philadelphia. The latter group is funded by progressives, LGBT activists, and labor unions, including the American Federation of Teachers.