This from Nate Silver at FiveThirtyEight:
It's no wonder the Romney camp is floundering all over the place. The ridiculous attacks on Obama over the Libya crisis are a sign that Romney is getting increasingly desperate and doesn't know how to mount an effective attack on the President. We witnessed exactly the same thing in '08 when the McCain camp went into overdrive and had Sarah Palin accuse Obama of 'palling around with terrorists', then got McCain to suspend his campaign to ostensibly deal with the financial crisis. Obama's preternatural cool is flummoxing his opponent and forcing him to act irrationally, and it is compounding his problems.
The race isn't over by a long way, but Romney's route to the Presidency is becoming less clear every day.