Just wanted to post my 2 cents on this topic.
First off I would like to say that there is a significant difference between opposing the war and supporting our troops, politicians (R and D) would like you to believe they are one in the same. I personally do not believe that Bush's reasoning for going into Iraq was well founded (Iraq had nothing to do with 9/11 and has never been directly connected with a terrorist attack on the U.S., Hussein was an evil man, but he wasn't stupid) but was more of an opportunistic agenda movement. That being said I have several friends over in Iraq right and now and have lost a couple more. I am not for an all out removal of our military forces, not because I believe we should finish what we started but because if we don't make sure that there is a stable government in this area we will be back over there again in 10-15 years doing the same thing and costing more lives in the process.
Will this war be "won", probably not. No matter what we do over there and how long we are there, we will eventually become a non-presence there and then they are on their own. This area of the world is very unstable. It has been for hundreds of years. There is very little to nothing we can do to change this fact.
Now to respond to the OP's post. Should Pelosi say these things, of course she shouldn't. Is the war a "failure", no we are obviously making headway towards the goal that was set fourth 6 or so years ago. Did we grossly underestimate the effort it was going to take to succeed in this situation, most certainly. The war itself is not the problem, as many of the posters have alluded to, it is the people behind the scenes that seem to cause the issues.
Politicians, IMO, are the problem with the Iraq war. We are there, we have lost many men and women fighting for another countries sovereignty. We have spent billions upon billions of dollars in this effort. What has this brought us? Our economy is starting to fail due to remarkably inept spending practices. Lowering taxes is the buzzword of the moment (as it always seems to be come election time). One huge problem with lowering taxes, where is the money coming from to fund all of this extra spending? We are still spending and spending to support this effort (and don't take this as we should cut spending for our troops, I think that would be the worst possible thing to do at this point) and politicians just want to look good by putting money back into the pockets of Americans. Unfortunately Joe Sixpack agrees. The same Joe Sixpack that is all about war and thinks we should keep sending more and more troops over. The same Joe Sixpack that thinks we should bring all the troops home. Politicians are failing us, not the war, and most certainly not the troops. But by saying the right things these people continue to run our country. A quick side note on this point, taxes are the money we use to run our country, without taxes our government would fail the way it is set up now. Can a government run without monetary support of it's people, yes, but not the way ours is set up right now.
Unfortunately over the past few years this war has become a political device more than anything else. Democrats are using it as an example of Republican failure and Republicans are using the Democrats lack of support as being "unpatriotic" There are several different permutation of this, but in general most of it boils down to this. This is DISGUSTING, war is not an instrument to get your party elected. There are a few politicians out there that do not allign with their parties beliefs, and are quickly dismissed by their opponents within that party as really being a "opposite party member".
I think this is more like a nickels worth, but I'll stop there for now. I just want to end by saying, support our troops, finish the war, and move onto more important things, like fixing our own country. Whatever it takes to make that happen, do it.