Why will Obama lose this election?

Because this election is the "New Kid vs. Established Candidate" scenario. Just like 1976, 1988 and to some extent 1992. In each of these elections the "new kid" jumped out to a lead and then tried to hold on. In 1976 (Carter) and 1992 (Clinton) they were able to hold on, but Dukakis in 1988 miserably crashed and burned. With this election so close now, Obama has no place to go but down.

I actually see a reasoning behind this. Most people know the established candidate, in this case John McCain, and they've known them for some time. Therefore, their vote is more solid, i.e. less likely to change. So what if their candidate makes a slip up or has a bad debate, they have a "body of work" that their supporters can feel comfortable with.

But how well do Obama's supporters know him? As the new kid, he has the appeal of freshness, much like Peanut-brain and Dukakis did. As the newness and novelty wore off, their support went down. Those who oppose Obama because of his complete lack of experience probably won't change their minds, as Barack won't get much more experience in the next few months. But everytime that inexperience leads to a gaffe, or the inner politician in him comes out, he will lose votes. In simple words, McCain's support is probably more reliable than Obamas. Both Carter and Clinton had big leads, so they were able to survive their dwindling support. Obama has already lost that lead, and it will just get smaller.

Just my humble opinion