That's true. After Tet 68, Cronkite pontificated that we had just lost the war in Vietnam and the politicians took him at his word. But I think what McNamara was talking about was that very thing... that the crop of politicians at the time, just as with the current ones, did not have the WILL to see it done... He obviously did not...
And Dubya does not have the will to do what should have been done from the beginning of Iraq: Go in full-bore and don't stop killing people and breaking things until there is ZERO opposition from either the Sunnis OR the Shiite-heads. He tried to fight a "compassionate" war instead of a war of national survival and then tried this "nation-building" thing, for which there is no Constitutional provision. Now I think it's too late in Iraq to go back to the "right" kind of war, so what do we do?
We have no choice. We fight on until we win. Surrender would be disaster. Not only for us and the Iraqis, but for the entire Middle East and for the world.
I'd drop leaflets giving the residents of certain neighborhoods in Baghdad 24 hours to get out of Dodge, then I'd level them. Burn out the Jihadists' hidey holes, then kill them as they flee.