But what about a game-changing event? Gaffes like Romney's 47% remarks have shown no ability to move the polls. Debates, as John Sides points out, have historically almost never made a difference. A foreign policy fiasco would almost certainly result in a rally around the leader effect, a la Carter in 1980, before the incumbent gets blamed. There isn't enough time for the "blame" part of the equation to occur before the election.It's that last one that I need to talk about. It's not actually true that all major foreign policy events yield a positive rally effect, and certainly not true that all fiascoes yield a positive rally effect. This is one that regular readers will recognize because I've talked about it many times: it turns out that sometimes there can be no rally or even a negative rally. For example, there was no rally during the Libyan intervention last year. The biggest slump? The Iran-Contra affair in November 1986 produced a huge drop, with Ronald Reagan's approval ratings dipping 21 points (a dip that lasted for months, in that particular case).
So, yeah, something going wrong in the world could certainly hurt Barack Obama in the final weeks of the campaign. No guarantee it would; some events produce the rally that Enten is talking about even if they objectively appear to be failures.
Looking beyond the rally effect, bad news at home could surely hurt Obama this late as well (just as good news could help him). It's true that the later we get, the less likely some event like this will happen. And while I don't know if there's any specific research on this, I would guess that events at the end of a campaign would tend to get swallowed up by the campaign; the campaign cues everyone to switch to maximum partisanship, and so presumably voters will tend to see events through a partisan screen and therefore tend more than usual to simply reinforce their prior opinions.
But that doesn't mean that events couldn't change the election this late. If Obama really does have a solid lead this late (and I'm still being cautious about that), I agree that it's very unlikely that campaign events would undermine it. Events in the world, however, are another story. It's not especially likely that a major new event would happen, and there's no guarantee at all that such an event would hurt and not help Obama, but I'm not aware of any reason to say that an external event couldn't make a difference late in the game.