If Obama has to disown a man he has never had anything to do with and a man whose toxic racist politics Obama has consistently and continuously opposed with all his might, then every black candidate is forced to jump through Cohen’s petty little racist litmus test. They’re all guilty of anti-Semitism until proved innocent. And Cohen’s transparent disavowals of such an insinuation make it worse not better.

We are learning a lot through this primary process – especially about some powerful white liberals and race. What we’re learning isn’t pretty.