Sources close to Biden said he was out-of-sorts as he traveled around the Atlanta area on Thursday. The former vice president, normally known for his garrulousness, was disengaged from the people around him, these sources said, a pensive mood supplanting his usual ebullience.

Behind the scenes, even some of his own team grumbled that they were uncomfortable with his position. “It was a real problem,” one close ally said. “I think a lot of people felt like it wasn’t going well.”…

Outside of Biden’s orbit, Democrats were left scratching their heads about what had happened — and pondering whether the former vice president had suffered any lasting political damage.

“I suspect that his campaign realized very quickly that this is an issue that is non-negotiable in a Democratic primary,” said Karen Finney, a senior advisor to 2016 nominee Hillary Clinton’s campaign.