I'm sure the survey is correct in that those who claim to be evangelicals responded in such a manner. I'm just don't believe they represent true believers in Christ and are not what we would consider a true evangelical. It's a matter of definition.
But to the contrary, when only 20% vote Democratic (80% Republican) in Presidential elections than it means that a Democrat supporting evangelical is a manifest aberration. Note also that in an election you often vote for the relative best out of a poor bunch of candidates, but while you can be a conservative and not be Christian, you cannot act/vote as a informed Biblical Christian and not be social conservative.