That ordinarily would be true except that Obama voters don't mind 0bumble's policies,if they are even aware of them.
The True believers will still vote for Obama; that probably represents about 40% of the voters last time around. I'm convinced he got about 10-12% of the vote from a combination of blacks voting for the very first time, just because he was black, whites voting because of 'white guilt', and younger voters who wanted to support the 'cool black guy'.
I think many of that 10-12% will have become disenchanted by Obama's horrid policies, especially those who are now unemployed because of his decisions.