Because it works

Why McCain is going so negative - Jonathan Martin - Politico.com

“Every day not talking about the economy, the war and how to fix a broken system is a victory for McCain,” said John Weaver, a former top strategist to the nominee who left the campaign last year. “They’re going to ride it as long as they can and as long as the mainstream media puts up every ridiculous charge.”

The negative and often exaggerated or misleading claims being made about Obama and Delaware Sen. Joe Biden, especially those playing on Palin’s gender, are just too irresistible for the process-consumed online and cable news media that now drives the campaign conversation, Weaver said.

“Unless there is a hurricane, they’re going to cover it,” he observed.