Another Clinton Superdelegate has switched support to Obama. As the media and supporters for each side recalculate the delegate count, they should not lose sight of the fact that a delegate can and did change a pledge. The only delegate count that matters is the one taken at the convention.
Not only can Superdelegates change their minds, pledged delegates can, too. The identities of the Superdelegates are easily known. Superdelegates often hold positions where they can be held accountable for their votes. That is not true of pledged delegates. Most of us do not even know the names of the people we are counting on to represent us at the national convention.
I don't know how often a pledged delegate has changed his or her vote from one candidate to another at the convention. Delegates tend to be passionate voters, thrilled to be part of the political process, eager to publicly vote for the candidate they have supported through the primary season, even if that candidate has no chance of winning. But that doesn't stop campaigns from trying to win over delegates pledged to another candidate at the convention. I know. I was a delegate for Gary Hart at the 1984 Democratic Convention.