because McCain loses if he talks issues

"It's now clear that John McCain would rather launch angry, personal attacks than talk about the economy."

From the Obama campaign:

"It's now clear that John McCain would rather launch angry, personal attacks than talk about the economy or defend his risky bailout scheme that hands over billions in taxpayer dollars to the same irresponsible Wall Street banks and lenders that got us into this mess – a scheme that guarantees taxpayers will lose money. While Barack Obama ensured that the rescue plan that passed Congress protects taxpayers and homeowners, John McCain's scheme has been panned by experts and observers from across the political spectrum," said Obama campaign spokesman Tommy Vietor.

(Americablog)