Let's suppose that the Obama campaign does want to sever their ties to James Johnson, although nothing apart from the campaign's silence gives any reason to believe that they do. Easier said than done. In supervising the vice presidential process, Johnson has put together independent teams of lawyers and a full staff; only he really knows how all the parts fit together. With Caroline Kennedy and Eric Holder on board, the circle broadens. But without Johnson, they'd have to essentially redo everything they've already done.