Where did he explain that? I must have missed it because each debate I kept waiting for some kind of explaination. He said he was going to take a scalpel to cut away spending, but he never mentioned just which programs he was going to slice up. At least McCain says he's going to start cutting spending in the agencies themselves first.
To me, it's just common sense that is the government wants to start all these new programs that other programs will suffer because they aren't considered as important (probably the military will be the first to be cut), or people are going to be taxed more.
...as estimated by the Committee for a Responsible Budget and reported by Kiplinger:
PDF side-by-side comparison: http://www.newamerica.net/files/usbw0915promises.pdf