The whole time during the last Presidential debate, Mitt Romney looked like the incumbent and Barack Obama looked like a challenger trying to keep it together. More specifically, Barack Obama, when he made eye contact, looked like he was seeing and invisible hand writing "Mene, Mene, Tekel, Parsin" on the wall behind Bob Schieffer. This was a man who knows the gig is almost up.
Throughout the debate, Mitt Romney smiled, agreed, and avoided fights. Barack Obama did everything he could to get into fights. That's not what incumbents in a comfortable lead do.
The biggest issue to come out of this debate, though, was Barack Obama totally claiming that sequestration was Congress's fault — he signed it into law — and that it would not happen, despite it being the law of the land.
Within mere moments after the conclusion of the debate, the Obama camp already walked it back. It is never good for the President of the United States when, immediately upon conclusion of a must win debate, his campaign team is already walking back his bold statements. His jokes about sequestration will haunt him in military towns and his dismissiveness of the American Navy will hurt him in key swing states.
Mitt Romney won this debate. Barack Obama, by the end, when not distracted by the handwriting on the wall, must have secretly been contemplating how good a deal he could get from U-Haul on moving boxes.