Well first let's give credit where credit is due. Obama is an amazingly good communicator and his ability to inspire people is exceptional. He is a leader. (my problem is with where he is leading). I also think his race helped him. It turned out the minority vote strongly and a lot of people wanted to vote for him to prove to themselves and the world that we are not racists
Second the Republicans have not given the voters any reason to love them. many of our best and brightest were corrupted by Washington and developed the arrogance of power. They discarded Republican principles in order to win reelection.
George Bush made some big mistakes. That turned the nation against him. Don't get me wrong I believe he is a good man and he did not get credit for a lot of the good things he did but lets face it he made some errors. I will argue forever that what we did in Iraq was just but in hindsight it was a mistake to do it. ( a full discussion of that may be a separate post). Then he mishandled the dam thing for 6 years. We lost the PR war when it came to "rights of Terrorists" I am not sure why we lost on that but it has had negative consequences for us. I could go on but fairly or not the American Public lost confidence in the President and that negatively effected the whole party.
Lastly Poor timing. An economic disaster occurred at the wrong time. Lets face it the party in power when the bubble bursts gets the blame whether they deserve it or not and I have seen both Democrats and Republicans burned by that.
Considering this perfect storm McCain didn't do half bad.
Some of these things we can fix. So enough Post Mortem. Get up off the ground. The next job is to design a blueprint for success.