Sorry, you can NOT be an Evangelical and vote for Obama! That means that either our definition of Evangelical is wrong or we have loosen the idea so that anyone can define themselves as an Evangelical with no idea what that actually means!
The short version is that we do not have Evangelicals that would vote for Obama - otherwise, they could NOT be Evangelicals - a major contraindication here for me!
In reality NO REAL EVANGELICALS would ever vote for Obama!
Well, yes & no.
I mean, you could say that no early Christian who was a true Christian would be sleeping with their mom-in-law; but the church @ Corinth had that...and the apostle Paul addressed it.
(You have even less church discipline these days...so there's ALL kinds of people on the rolls of church membership lists...and remember, Jesus said that the tares would be among the wheat...)