Presidents have long engaged in the bareknuckle boxing of partisan politics. Consider, for instance, FDR’s famous “Fala Speech.” I wouldn’t fault Obama per se for such partisanship, although I think he has been much more direct and personal than he should be. He’s also terribly humorless, which makes it seem like he is whining. Check out the video of the Fala Speech for an idea of how much more effective a partisan hit can be when it has a light touch. Also, check out Hillary Clinton’s 2008 DNC address for a deftly-crafted shot at the Grand Old Party.

What’s peculiar about Obama (beyond the total lack of good cheer) is that he campaigned against the very type of partisan warfare he now engages in. Remember the Red State/Blue State speech from the 2004 DNC? It’s no easy feat to reconcile that with the accusation that the Tea Parties are stocked with racists. Similarly, peruse the pages of The Audacity of Hope and try to square his self-righteous paeans to genuine bipartisanship with his suggestion that FOX News is “destructive for the long-term growth of” America.

What explains this transformation in President Obama’s attitude? How did he go from being the candidate who promised post-partisanship to the president who all but accused Mitch McConnell of playing the fiddle while Rome burned?

I can think of four potential explanations.