The question about the Edwards endorsement is, Why Now?
1. He probably thinks Obama has it locked, and it's time for it to end.
1.5. He probably thinks that since Obama has it locked, it's not a healthy thing for him to be suffering 40-point losses in Appalachia.
2. In between West Virginia and Kentucky, on the assumption that white working class voters actually listen to him, he can maybe do Obama some good. He got 7 percent of the vote in WV last night. Maybe he can help cut that 40-point margin down.
3. Will he actually campaign for Obama in Kentucky?
4. It's probably the last moment where his endorsement has some real value. So, as a pure political calculation -- which is what it appears to be -- it was now or never.
5. He could want support for his issues (poverty, especially).
6. Even though he says he's not interested in VP, maybe he is.
7. Maybe he got annoyed at something Clinton said. But her comment about white voters was last week, and she seemed to be on her good behavior last night in WV.