Biden was first questioned about the growing controversy by CBS News campaign reporter Bo Erickson just days after it began. At the time, Biden responded by calling the story a "smear campaign" before scolding Erickson for questioning him.
"I knew you'd ask it. I have no response, it's another smear campaign, right up your alley, those are the questions you always ask," Biden said.
What happened this time?
During a campaign stop in Pennsylvania on Saturday, a reporter attempted to ask Biden about the story — but Biden cut off the reporter, lashing out before the reporter could even finish his question.