I think you underestimate Obama’s cult-like following.
There's someone else in the race that also has a cult-like following: his name is Ron Paul. Personally, I know some 'Paulistinians' who months ago thought that he was the Second Coming, but are now realizing just how badly he would screw up foreign policy and are taking a second look at McCain. Many on the 'Rat side that are swooning over Obama now will probably do the same as the election approaches.
At the end of the day, I really believe that unless the 'Rats pull a rabbit out of their hats at the convention, McCain is the next POTUS, as both Hildabeast and Obama have too many fatal flaws. According to John Derbyshire on NRO today, that rabbit may very well be named Al Gore.
I think they overestimate it. The cultists are all Democrats I cannot conceive what Obama could say to win over most Republicans and independants. I am curious to see what Obama does to get back toward the middle for the general election. He crawled left of Clinton now he has to get back toward the middle.