If so, it may be a short term effect. I am afraid that his strategy of blessing a formal investigation of the so-called "intelligence failure" may actually defuse this issue for the purpose of the November election. All he needs to do is to say "You cannot blame that on me - I started an investigation after all." Of course, that may change if his administration is found guilty of manipulating the intelligence data, but if that finding comes out AFTER November election, it will not hurt him very much. It looks like a clever ploy from Karl Rove's shop.
My own view of Bush's support (or lack thereof) is that the 9/11 effect is wearing off and we are returning to November 2000. That is to say, Bush got a slight minority of the popular vote in November 2000 and those who supported him then continue supporting him for reasons other than "the war on terror," low taxes, no welfare, no gun control, lib'rul bashing, etc. His spike in popularity was due mainly to the 9/11 effect - people who feel threatened close their ranks behind their leaders, especially when those leaders are not challenged. So as long as democrats played Bush's lap dog, most people saw him as the :only alternative we have" and that was reflected in the polls.
However, when the Democrats finally started to challenge Bush (thanks mainly to Dean), his appeal to 9/11-scared crowd diminished, and his support level goes back to where it was before 9/11. That makes me think that it 2004 will be another very close call (similar to 2000) and the Repugs might try another trick - fixing voting machines, purging likely Democrat voters from the voting lists, absentee ballot fraud, another staged anthrax scare (the recent ricin scare may be a 'dry run') to name just a few - to prolong Bush's reign.
As Marx one said "history repeats itself, as it were twice; first time as tragedy the second time as farce." November 2004 might be a case of that.
Wojtek