Which Voting Block Matters More To The Democrats?

From the June 6, 2012 Quad City Times:

DES MOINES — A prominent leader in the Iowa/Nebraska branch of the NAACP — the country’s oldest civil rights group — announced today that he is resigning as branch president and a national board member in the wake of the national organization’s decision to endorse marriage between people of the same gender.

It's a funny thing, but blacks are generally much more socially conservative than whites, with very solid majorities of black Californians voting for Proposition 8 several years ago.  Obama has been getting a lot of flack from black church leaders about his endorsement of same-sex marriage.  I suspect that quite a number of blacks who aren't so prominent are having the same reason as this guy.  I doubt that it will cause lots of blacks to vote Republican--but I could sure see a lot decide not to vote at all this time around, or not vote for president at all.

Let's see: blacks are about 11% of the American population, and probably 12-13% of the voters (because they are overwhelmingly U.S. citizens, unlike some other segments that are heavily immigrant).  In 2008, somewhere between 95% and 99% of American blacks voted for Obama.

By comparison, gay, lesbian, bisexual, transgendered, intersexed, and all the other oddball categories that now make up that group are at best 3-4% of the American population.  About 1/3 of that population still votes Republican, because there are issues that matter more to them than same-sex marriage.

So Obama is going to irritate a big chunk of the 12-13% of voters who are guaranteed Democrat votes in order to mobilize voting and campaign contributions from about 2-3% of the American public.  This seems like a rather poor trade-off.