Pennsylvania Sen. Bob Casey, an Obama supporter, makes an interesting point on CNN:
Clinton, making the case for her electability, has to argue that Obama has some fatal weakness among certain groups (especially, blue-collar white voters).
But in doing so -- she undersells her own strength.
The primary has featured two exceptionally strong candidates with strong bases. The result of that is that, inherently, the winner is going to look exceptionally weak -- losing nearly 50 percent of the votes.
But against a less formidable opponent, Obama might look much stronger. Same with Hillary.