I think when Obama ran the first time he thought he needed the left's help.

As soon as elected, he jumped toward the right. I think he decided he no longer needed to be concerned with the left as they had no where to go and he concentrated on winning the hearts of the New Democrats (converted Republicans).

The strategy was smart. As I see it, if you convince a non-voter to vote for you, that's worth one vote. In other words if the score was 10 votes to 10 votes and you got a non-voter to vote then the score would be 11 to 10. If you convince an opponents voter to switch that is worth two votes. A 10 to 10 tie would change to 11 to 9. So if you piss off a left voter by nominating Penny Pritzker, for example, you might lose a left voter and gain a middle/right voter. So this would result in a 10 to 9 result. So losing a left voter and gaining a right voter is a smart strategy. In fact, I think statistics show that only about 25% of the pissed off left voters actually refuse to vote, meaning you would only be losing 0.75% of a vote by pissing off the left, leaving you with a 10.75 to 9 margin by wooing the right/center.