CHARLESTON, South Carolina — With every gaffe he made, and there have been plenty in recent days, Joe Biden placed a greater and greater burden on himself at Tuesday’s Democratic debate at the Gaillard Center in downtown Charleston. Each screw-up made his supporters more and more anxious and, therefore, more and more eager (desperate?) to see him deliver a reassuring performance.

“This debate is really, really important to him,” one state Democratic politico said an hour before the debate began. Many Democrats, he explained, spent Tuesday discussing Biden’s cringe-inducing self-introduction at a party dinner the night before: “My name’s Joe Biden — I’m a Democratic candidate for the United States Senate.” While some shook their heads, Biden did not correct himself.