Nate Silver notes Obama now has a net negative approval rating for his handling of Libya — 49% disapproval vs. 42% approval in the latest ABC/WaPo poll. Interestingly, though, poll respondents aren’t necessarily against the humanitarian mission: 56% support US military aircraft participating in the “coalition of international forces [that] has been enforcing a no-fly zone over Libya, and attacking Libyan forces when they’re believed to be threatening civilians.” So why doesn’t Obama get higher marks? A third question gives a hint: Of those who support the humanitarian mission, 58% say the military action should seek to remove Gaddafi from power. Doubts about Obama’s incoherent approach on that point seem only natural, and are likely to grow as long as Gaddafi survives.