Back when I used to hang out on T_D, I would often see the claim that if the democrats lost just 10% of the black vote, they would never win another national election. Whenever I asked, nobody would back up the math behind 10% of 13% being so important, they'd just ignore the question and go repeat the claim in another thread. Also, nobody would ever answer why no major candidate ever courted the largest voting aged ethnic group in the country, White people.