...The 2004 presidential campaign is being fought as aggressively over the airwaves as it is on the hustings. With many states up for grabs, candidates and their allies are using tailored broadcast ads, like the DNC's Pittsburgh spot, which are also called "tracking" or "pre-buttal" ads. These spots, an advertising innovation this election, are prepared for specific markets and run around the time the opposing candidate makes a campaign appearance. Tracking ads are cheaper and easier to produce than national ads, but can be just as effective.... President Bush's campaign cut the first tracking ad, which coincided with a visit...