Have you? There's this thing called a veto... might want to read about it. You and W.
Yes, I have read it. Congress holds the purse strings and makes the laws. Since the people ELECTED congress and the senate to do that job a veto should only be used rarely especially if the congress and senate are of the same party as the elected president.
So, when Congress attaches unnecessary spending to very necessary spending in support of the war, you favor cutting off funds to support the troops in harms' way, and forcing the President to take all of the heat for it.