The question itself rests upon some unspoken assumptions.
First, will voters consider a black candidate for President based upon his ideology (values, policy preferences, etc.) apart from the color of his skin? (We'll set aside the complicated situation when color itself constitutes part of one's ideology.)
Second, will voters evaluate a black President in office based upon performance?
It appears that self-professed "Progressives" are still not ready for a black president.
President Barack Obama, our first black President (if we exclude Bill Clinton) has come under withering criticism from conservatives. Conservatives base their criticisms partly on ideology. They believe that Obama's progressive ideology deviates from the Constitution and that it lacks a "fit" for the way the world really works. They also base their criticism on his poor performance. The clumsy "Fast and Furious" gun trafficking operation, the failure to respond to the attack at Benghazi, and even the muddled roll out of his "signature accomplishment" of the ACA suggest an administration plagued by incompetence.
Progressives attempt to shut down such criticism based upon both policy and performance with an appeal to race. Most recently, this occurred in a piece of news "analysis" by MSNBC by Melissa Harris-Perry in which she likened the work "Obamacare" to "nigger" :
Of course, Harris-Perry's charges are hardly original. They have served as the staple of Progressive apologists for the Obama administration since its inauguration. Here is Chris Mathews:
And the second worst president of the United States, who until recently surpassed all others as THE worst, Jimmy Carter:
Perhaps once the Obama administration has run it course and Obama joins the pantheon of ex-Presidents, Progressives will be able to overcome their dermatological delusions and take an honest look at the Obama administration.
Perhaps once Americans elect a black Republican president, Progressives will be able to assess a President through other than