This one doesn't take a rocket scientist. Hell, rocket science doesn't take a rocket scientist for some.
The reason why the Republicans lost is the War in Iraq. Regardless if it was right or wrong, that's what happened. The public was fixated on it. The difference between Bush's re-election bid and these Congressional elections can be summed up with that primary difference.
Kerry wanted to make the election about Iraq. He failed miserably. Instead Karl Rove was successful on making the election about those contentious Moral Issues... You know the ones we're told repetitively make Conservatives loose elections both in the Dominion and in the US?
Social Conservatives for the most part can be broken down into two groups: religious people, and everyone else. The "everyone else" category I think is safe to say a minority group among Social Conservatives.
Religious people aren't exactly raging Bush-a-holics. They've supported Bush in the past only for his moral stands. Many of these people are in fact very liberal. They frequently have an overabundance of charity and don't see Republican laissez-faire economics as being quite so. No matter how wrong they are that's what the majority of them believe as far a Your Humble Servant is concerned.
I've had the unique experience of learning that first hand. Being quite politically conservative before becoming religious, I understand quite clearly that most Christians see the world in an economically liberal, socially conservative bent.
Now part of that bent comes from the fact that western society is just quite frankly very Liberal today. We have to admit that fact. We live in a society that believes firmly in government intervention in our daily lives. The days of distrusting the state are in the dust bins of history if it ever existed at all.
And for the most part these types of social conservatives don't like war, and especially not the War in Iraq. When the focus is on moral issues they flock to Republicans. When the focus is on the War in Iraq the opposite happens I think.
I believe that despite their small size, the dwingdling love-in between social conservatives in the US and Bush because of the War had a large part to play in the loss last night.
But that's just one Canuck's opinion.