In a clear reference to Bernie Sanders and Donald Trump supporters, President Obama told CBS in an Tuesday interview that sometimes voters let their "passion" do the picking for them, instead of using reason. This article sums it all up:
"In an interview with CBS, President Barack Obama admitted that he was surprised by the rise of presidential hopefuls Donald Trump and Vermont Sen. Bernie Sanders. But that surprise only goes so far, he said, because at this point in the electoral process, voters are behaving more passionately than practically. The pre-recorded interview aired on Tuesday." www.attn.com/...
Obama has made it clear he prefers Clinton over Sanders.
If I were Sanders I would not respond to Obama, lest his paltry support among African American voters sinks further.