Running as not the challenger

It's normally "I'm not the incumbent". [Link]

Lots of presidential candidates have run on a platform of Not The Incumbent, but Obama may be the first to define himself entirely as Not the Challenger.   One of Romney's pollsters suggested to USA Today that this has been a costly decision, as the Mitt Romney people are seeing in the debates doesn't look much like the horrific, granny-killing, woman-hating GOP monster that Obama has been running against.  Which may be why the gender gap, which has been giving Obama a big advantage, has started to close:  

"In general, women tend to be later decision-makers than men and the Obama campaign has gone out of their way to run a negative campaign against Governor Romney among women," Newhouse says. "The first debate had a significant impact on these voters as they watched it and Governor Romney appeared nothing like the candidate that was essentially a caricature in the advertising by the Obama campaign. It's these voters who began to realize that the picture being painted of him was not reality."  

Of course, this is Romney's campaign talking, so take that with a big grain of salt.  However, I suspect that the core implication is correct:  Obama is not going to make it across the finish line solely on the basis of who he isn't.  He needs to set out some sort of affirmative vision for the second term, however low the chances that he will actually see that agenda into legislation.
The problem, I suspect, is that after four years, Obama knows all too well how unlikely Hope and Change actually are. And if he just repeats the stuff he promised the first time around, voters are likely to ask "Why didn't you do that already?"
Reagan and Bush could argue that they'd done popular  things in their first term that they needed to follow through to the end.  Very stupid popular things, in the case of the Iraq War, but this is neither here nor there.  What can Obama say that about?  Obamacare?  Voters would rather he not, thanks.  The stimulus?   Best not bring it up.   As long as voters thought Mitt Romney inauthentic, yet a terrifyingly rabid right-wing ideologue, Obama didn't need an agenda; he could just run against the terrible things that Romney would do.  But over the last few weeks, that hasn't been working as well.