If one parses through the exit polls for CA Prop 8, the measure would have still passed (albeit with just a few tenths of a percent instead of a little over 2%) even if all black votes removed, never mind if just the "extra" blacks attributable to Obama's run had their votes removed.
Sure, the blacks who voted supported Prop 8 at a 70% clip. There are several other groups that are larger and supported the measure at a higher right.
Which was the most influential group?
McCain voters (a group far larger than black voters), who supported Prop 8 at a 85% rate. Not much was said about this group for some reason.
As to the matter of the vote on hand, it's probably worth noting that CA blacks are not going to be equivalent to the broader class of blacks in the USA, who will not be equivalent to the class of Congressional blacks who represent their respective districts.
It's fairly nonsensical to talk about groups of people who support a certain issue at a certain rate. You can't speak for everyone in that group, because they do split their vote.
I will say, though, that 36 of those 37 voting members did the right thing.
