Rudy has a firefighter problem, more specifically a NYC 9/11 firefighter problem.  TPMCafe notes that the head of the firefighter's union there has "vowed to sink his candidacy".  Rather than taking shots directly through the press at him, here is my suggestion.

Get the union to pay for a few firefighters to take a leave of absence for the campaign and have them follow Giuliani from event to event.  Get them in their t-shirts, work pants and boots holding signs in front of big fundraisers, or outside of rallies.  Have the local unions in the area send some guys in solidarity and get a whole mess of firefighters protesting.

We used this technique to great effect in the special election in 2005 here in California.  The campaign branded the phrase "teachers, nurses, cops and firefighters" and had people in scrubs and uniform dogging Arnold at every step.  Anytime one of the local stations did a story on an Arnold campaign/official state business stop they had to do an obligatory cut away to the crowds out front.  Even if it was only a handful they had to cover that angle.  The earned media was literally worth millions.

You can do the same thing with these firefighters.  It won't be cheap, but get the International Association of Fire Fighters to pitch in to cover the costs.  The media rewards will be more than worth it.  They won't be able to ignore the story of some 9/11 firefighters protesting their former mayor.