Iraq War Question

The presidents approval rating it at 33%. How is it that the majority of Americans changed their mind about the president. He said that we were going to Iraq and that we'd be there for a while. He went and we've been there for a while. He said what he was going to do yet he was still elected president. Some people said that they were duped and that he and his administration lied. Of course they did it was obvious that they were doing it at the time. The U.S. government itself said all of the evidence was speculative. A lot of people are now saying that he is not a very competent president. He hasn't changed. But I'm getting off topic. I don't like Bush or his administration but is it right to be upset and angry with Bush & Com considering that they told you what they were going to do even thought the evidence was faulty and known to be faulty? Is it Bush's fault for misleading us or our fault for allowing us to be misled?