Huge generalization here, but this is one major reason why I'm not a Republican and haven't been for nearly 10 years. I'm not a Democrat either, but if I had to pick one party, I'd be a Democrat.
Too many Republicans make it a virtue to vote for someone
like them. That's one reason why Sarah Palin was popular at first-
lots of women liked her because she was a mom like them even though she
would have been totally incompetent at running a country, and why Mitt
Romney had a rough time in North Carolina yesterday. Conservative Christians who make up a significant part of the Republican party base won't touch Romney.
Democrats make it a virtue to vote for someone not like them.
There is no way there could be a Republican candidate like Obama, not
with his supposed ties to Islam and his ethnic background. But since he's a Democrat, it's not a problem, or maybe even an advantage. Have you ever heard anyone care at all that Harry Reid is a Mormon?
In both cases, a
candidate's religious, cultural, and ethnic background matter. Those
aren't necessarily good things to base a vote on. But since that is
something lots of people base their votes on, I'd rather go with the
party who votes for diversity instead of someone just like me.