The surest sign that the war is being won is that it has been falling out of the news. The victory comes when our combat troops have been withdrawn and Iraq remains stable without them. This withdrawal is already in progress. The army, in its usual combat relationship with the English language, has been quietly working on "building down" its post-surge troop strength in Iraq. The shape of the evolving "peace" has just been demonstrated in Basra in forcing Bani Sadr's Mahdi army to stand down without a prolonged fight. It was done with Iraqi army infantry and American air power.
The domestic politics of it are ironic unto humorous. The Bush Administration wants the war won while they are in office. The McCain campaign ought to want the war to go on so they can elect an old soldier to conduct it, in preference to the openly defeatist Democrats.
The Democrats, on the other hand, will benefit greatly from the war ending before either of them gets to the White House. Their plans to withdraw may or may not help them get elected. But it will be politically disastrous for them if they actually do withdraw the troops after taking office. When the news stories of widespread beheadings and Iranian influence and renewed ethnic cleansing start to come out of post-withdrawal Baghdad there will be such a public clamor that impeachment will be possible, and defeat in the 2010 midterm elections certain. If the war is not won before they take office ("Won" defined as the Iraqi government and army being in control of the country.), they may well be in big political trouble whether they withdraw or stay.
If the war is won or nearly so by the end of the Democratic convention and the beginning of the general election campaigns, it will be off the agenda. Without the war, the issues will all be domestic, i.e. the economy. McCain's announced policy of abandoning borrowers in foreclosure while the federal reserve board rescues banks, will hang like a millstone around his neck. That, and his announced "do nothing" economic policy, will sink him.
Democrats ought to hope the army can win the war and come home before they themselves can undo everything the troops have accomplished by withdrawing them before the war is won.