This cartoon is amusing, but the point is not entirely valid. Let's check the results from Obama's huge SC win

About seven in 10 white voters said they would be satisfied if Obama became the nominee; eight in 10 African Americans would be happy with Clinton as the party's choice. But here, too, there were differences in levels of enthusiasm. More than eight in 10 black voters said they would be "very satisfied" with Obama as the party's nominee, but 38 percent of white voters made the same statement.

So at 70% of voters would be happy if the other person was nominated. That sounds about right: there are always a few crazies on both sides, but that should increase as the nomination rolls around. The GOP side...well, I don't feel is the same at all.