That is one of the most disappointing things about the Bush Administration, that it never defended itself against attacks. I did not like a lot of what Bush did, but he did a lot of things right and could have defended himself. Instead he ended up a very unpopular president and probably cost the GOP the white house and Senate.
This is purely conjecture but I have wondered if Bush, in order to fight the war on Terror made deals with the Dems, even against his better judgment. We will never know if he would have been a much different President had 9/11 not occurred. What I do know is that, George Bush was a proud American and deep down would do whatever it took to protect this country. It could not have been easy with the left, who imho would use 9/11 and the WOT as a tool to manipulate him.