A new composite poll, from Steven Ruggles via Kevin Drum, shows how completely dependent Bush's approval is on "rally around the flag" kinds of moments.

It's nice to see his numbers in the toilet, and it's also nice to note that the spikes from the three highlighted events get smaller and smaller. This shows that many people have abandoned him and aren't coming back. They realize that capturing Saddam doesn't mean Bush is suddenly doing a good job, and the bad news is overwhelming any good.
The danger is that they launch an all out effort to get Osama sometime this summer or early fall, which would most likely lead to his capture. Hopefully people have seen enough by now to realize that nabbing bin Laden isn't much of a victory. It's far too little, way too late.
Another possibility is another terrorist attack in the U.S. which would inevitably produce a big bump for the president, but I'm not convinced it would be nearly as profound as it was after 9/11.
For the past 2 1/2 years we've been very aware of our vulnerability to attack, and suffering another major one could cause people to decide that the administration hasn't done its job. For most Americans, 9/11 was a complete shock, so we rallied around the president. Another attack would raise serious questions about how honestly the administration did its work of securing the homeland, and how our adventure in Iraq has completely distracted us and stolen massive resources from the real war on terror. Not to mention that the Iraq war has solidified worldwide sentiment against us, ensuring that far more people wish us harm than did before.
Consider this: If our strategy after 9/11 had been different; if we had kept troop strength up in Afghanistan to finish the job there properly; if we had used even a tiny fraction of the money we've blown on Iraq for intelligence overhauls, worldwide law enforcement efforts and more spies on the ground in terrorist organizations; if we had taken advantage of global goodwill after 9/11 instead of squandering it at light speed, would another attack be more or less likely?
In my opinion, it would obviously be far less likely.
I'm not sure that the overall "American Voter" sees things this way. Many, many people will think that if we change our leadership after an attack, we are allowing the terrorists to vote in our election. People make this argument about Spain all the time.
There are so many problems with this argument.
First and most important is that the terrorists DON'T CARE who runs our government. They hate us. They hate Republicans, they hate Democrats. They hate Ralph Nader. What is important in this regard is not what the terrorists want -- they want us dead -- it's what we can do about the people who aren't terrorists, yet.
Which leads to the second problem: If they do have an interest, why do we assume that it is in replacing George Bush? This is a completely simplistic way of looking at things. George Bush and his policies have probably been the best recruiting tool Islamic terrorists have ever had. This argument also assumes the ridiculous idea that if John Kerry wins, we'll suddenly just stop fighting terrorism, as if to say, "Oh, terrorism? We're okay with that now. It's really not so bad. Go ahead. Terrorize away."
Imagine this scenario: You're a young Muslim. You're on the fence about this "great satan" thing, though. America didn't used to seem all that bad, the freedom, the prosperity, the MTV -- but now, well, things just look so terrible in your home. People are dying all around you, there is no freedom to be seen, and now you see these liberators torturing prisoners. Your faith in America is likely to fade fast. All of these shouting, radical clerics may have a point about some of this stuff.
Now, Kerry wins the election, showing that the majority of Americans don't agree with Bush's policies either. Your faith in America and democracy is somewhat restored!
Or, Bush wins, telling you that the citizens of America are on the side of the policies of the past 4 years, the policies which have driven you to radicalism. Pass the AK-47.
I find this to be a credible scenario, and one I could imagine happening in thousands of people's minds.
Whether it happens or not, the point is that our election will certainly send a message to the rest of the world, but it is not a simple thing to determine what that message will be. Simply assuming that a vote for Bush is a vote against terrorism is ridiculously shortsighted.
We should be voting based on what we want our country to be, what values we feel it should stand for, not based on fear. Do we want our country to be one consumed with fear and distrust, greedy beyond measure, and unable to see past its own nose? One that holds the world to moral standards that it can't begin to live up to itself? Or do we want a country that can stand up to fear and terror, not just with our great weapons, but with our hearts and our minds? Fear is the absolute greatest weapon of the terrorist. If they attack again -- and they will -- our great challenge will be to stand by our beliefs and our principles and not abandon them in the face of danger. The challenge will be to remember what it is that we're supposed to be fighting for.

