Why did Caroline Kennedy remove her name from consideration for Hillary Clinton's Senate seat? It certainly makes sense to imagine that Governor Paterson sent some signal that he did not intend to appoint her, giving her the opportunity to bow out on her own terms. I also find plausible Nate Silver's suggestion that, the further along she got in the process, the less Kennedy may have been sure that this was really what she wanted in the first place.
My own entirely unsubstantiated bit of speculation--which might help address Mike's question on what role her uncle's health could have played in the decision--is that perhaps Teddy was having second thoughts about the appointment. When news of his illness came out last year, the elder Kennedy made quite clear that he would like his wife of 16 years, Vicki, to inherit his Senate seat. And it's hard to imagine that such a succession wouldn't be at least somewhat complicated if his niece had been awarded a Senate seat thanks to her family name just a short time before. The emotional argument for retaining one Kennedy in the Senate, absurd as it is to me, would likely be strained beyond breaking if extended to two.
If Teddy tries at some point to bequeath his seat to Vicki, will it be met with the same resistance as Caroline's aborted bid? My guess is no. For one thing, it will help that she has been, by most accounts, one of her husband's closest
advisers and political confidantes for many years. But more importantly, there is a long history of senators and congressmen passing seats on to spouses and/or children, and it's not entirely without rationale, however strained. The idea--ratified most explicitly by the posthumous election of Mel Carnahan, whose Senate seat was promised to his widow--is that if voters elected a certain person to Congress who dies while in office, the person most certain to "carry on" his (or her) work is an immediate family member. (This is obviously a factor in family political successions that are not due to death or incapacity as well.) This strikes me as an exceptionally dopey way to choose a senator or congressman, but many voters obviously disagree. What made the Caroline Kennedy case so unique was that she was attempting to inherit a seat that hadn't been held by a member of her family for 40 years and, given her high-profile support of Barack Obama in the primaries, she could hardly be considered an obvious candidate to "carry on" the work that New York voters elected Hillary Clinton to perform.