Candidates take the role of the opposition while trying to differentiate between themselves.
There is no gains in attacking the President, especially from the democratic candidates; by doing so they do not differentiate from one-another, they just repeat common values while having a safe opposition strategy.
Hillary Clinton is attacking the President without differentiating from the rest of the bunch, while Edwards and Obama are talking about current affairs.
The democratic candidates need to understand that their opponents right now are in their own party, there is plenty of time to attack the President, and the republican candidate, once there is a final Democratic candidate.
Hillary's move not to differentiate from the others is setting her aside to be targeted. Obama and Edwards need to attack now in order to gain now.
The CNN Race to ’08 Podcasts are a great way to keep up with developments