I have read many times the claim that 200,000 registered democrats in Florida voted for George W. Bush in 2000. I happen to believe that claim, but I doubt most rank-and-file liberal democrats would believe it on face value, especially considering that a google of this turns up either Green Party websites (which arguably have a vested interest in making such a claim), blogs (which by themselves aren’t valuable without credible citations), or broken websites.
There is a great fear among most liberal Americans. The fear is what compels them to vote for vote time and again for registered democrats who are in favor of indefinite detention, cutting social safety nets, and granting clemancy to the criminal acts of the banks. The propaganda fueled by fear can only be fought with data from acceptable, mainstream sources that only the most blindly loyal democrat will deny.