Bush: Kerry Unable to Win War on Terror

ABC News: Bush: Kerry Unable to Win War on Terror:

'The next commander in chief must lead us to victory in this war and you cannot win a war when you don't believe you're fighting one,' Bush told hundreds of supporters in a northern Iowa farming community.

What exactly does Bush mean here? What does it mean to be "fighting a war", exactly? And what is it that Kerry has proposed that will prevent him from "winning"? Can anybody explain this to me? (send to mkvalsvik@yahoo.com)