Given how he would landslide if the electino was today, he obviously "could" win.
The Realclear politics averages have him up about 1 percent on both Obama and Clinton. You must be assuming Obama to be the nominee and also to have a healthy dose of Bradley effect thrown in as well (on top of the fact that the Bradley effect is probably already showing up in polls given the recent Wright flap has been so prominent in the news).
I think it's pretty unreasonable to say that the election would be anything other than close if held today; at the very least such as statement requires explanation as to why current polling is too favorable to Democrats.