Compared to their counterparts in the race for the Republican nomination, Ms Clinton and Mr Sanders have conducted a relatively cordial campaign. However, relations between the two camps have grown increasingly hostile in recent weeks.
Speaking at a Philadelphia rally on Wednesday, Mr Sanders said: “Secretary Clinton appears to be getting a little bit nervous.
“She has been saying lately that she thinks that I am not qualified to be president. Let me just say in response to Secretary Clinton: I don’t believe that she is qualified. “I don’t think you are qualified if you get $15 million from Wall Street through your super PAC.” Read more