The candidate: Businessman Tom Knox, Democrat

The ad: "How many?" a 30-second spot running on Philadelphia broadcast and cable channels.

Producer: Trippi & Associates, St. Michaels, Md.

Script and images: Teletypes clatter like something out of the The Front Page, and a clipping from The Inquirer appears. "The Inquirer reports his opponents are hatching plans to attack Tom Knox. Now the Daily News calls the anti-Knox campaign 'fishy.' (Another clip) And the Board of Ethics plans to issue subpoenas against those running the ads. Illegal smears and attacks. (Words flash on screen, then a black-and-white photo of schoolchildren.) "How many more children will we send to unsafe schools?" (a police cruiser) "How many more victims of violent crime?" (City Hall in black and white) "How much more corrupt politics that have failed our city?. . .before we say, 'Enough?' " (The word "enough" stretches across the screen. "It's time for change, Philadelphia." (Color pictures of Knox.) "Tom Knox, Democrat for mayor."

Analysis: A strong attempt to inoculate Knox from attacks on his business record from rival Bob Brady and independent "527" political committees. The ad conforms to Knox's so-far effective meta-narrative that city politics is slimy and he will hose it down. Factually, it is true the city Board of Ethics is pursuing an initial inquiry into whether there was coordination between a campaign and one of the independent 527s. But it is far from clear that is illegal: Some lawyers question whether federal law against coordination applies to local races, and the city campaign-finance ordinance does not directly address independent expenditures.

- Thomas Fitzgerald