I would say you are full of shit on your 10% guess.
More like 40-50% at least, it's hard to count really, because 'liberal white guilt' is hard to measure, it's well hidden. But I would say, aside from the 14% blacks who mostly only support him because he is black, there are at least 30% of the liberals out there, who also support him because he is black; Because they constantly charge 'racism' against anyone who criticizes him.
On the other hand... The GOP has a nominee who has studied every aspect of running for president the past 6 years, and he feels confident enough to float the idea of Condoleeza Rice as a running mate. One of the leading contenders for the challenge against Romney early on, was a black man named Herman Cain. Several staunch conservatives have mentioned Alan West, another black man, to be the VP pick. The most popular of ALL people in the GOP for VP, is Cuban-American. I see no indication that anywhere NEAR 10% of the party is overtly racist.