The interesting thing about Romney's defense today is that he says "even Jimmy Carter" would have ordered the commando raid on bin Laden's compound. But it's notable that Romney himself seems to have placed himself further to the left of Carter by saying that he wouldn't have done so. Or more specifically that he wouldn't have violated Pakistani sovereignty to mount the raid.
Also notable, Romney now seems to be arguing that the bin Laden raid was simply a no-brainer. That ignores the fact Obama's push for a greater emphasis on finding bin Laden and pressuring Pakistan was a key part of being in the position to call the raid. And since several of Obama national security advisors -- including, it seems, Robert Gates, the holdover Secretary of Defense from the Bush administration -- were either skeptical or opposed to the mission, it's hard to see how it really could have been such a no-brainer.
Expect a lot more of this. But also expect the Obama campaign to keep hammering the fact that Romney said he opposed both the policy of aggressively focusing on bin Laden and violating Pakistani sovereignty. It's hard to get around that.