US parties fight for prime Web ad space

Washington

IT turns out that the Internet does not have infinite capacity. At least not for political ads. As an increasing number of US political campaigns and outside groups are finding out, premium space on the web has long been booked. Digital advertising is maturing much in the way television did, as targeting becomes more sophisticated and the definition of a viewer expands drastically.

"Many political strategists don't think of the Internet as something that can sell out," said Rob Saliterman, leader of the elections team at Google, which owns YouTube. "But in these smaller American states, just as there's a finite amount of TV inventory, there's a finite amount of YouTube inventory."

The more savvy players in the coming US midterm elections made pre-emptive strikes to ensure ad placement when it matters most. In June, Tim Lim, the president of Precision Network, a digital media buyer for Democrats, began purchasing ad space from premium online vendors - Google, Yahoo, Pandora - in Senate battleground states like Colorado and Iow…