First, to make sure others are up to speed: President Obama's campaign announced last night that he was throwing in the towel on his somewhat-distant relationship with a super PAC, called Priorities USA Action, that was formed to help him but had terrible results raising money (unlike Obama's campaign itself, by the way).
Various campagn leaders and advisers, including Jim Messina and David Axelrod, have portrayed the decision as one of pragmatism--Axelrod said on MSNBC this morning that Republican groups were effectively "pointing guns" at the campaign.
It appears that a lot of events came together in recent weeks to push them in this direction, particularly the overwhelming dominance of super PACs in the GOP primaries and their ability to raise far more money than Democratic equivalents.



