As the sound cut in and out and the audio often came out garbled, Mr. Biden sought to host what his campaign had called a “virtual town hall with Illinois,” in which he spoke to supporters and voters via video in place of an originally scheduled Chicago get-out-the-vote event — or at least, that was the goal.

“I’m sorry this has been such a disjointed effort here because of the connections,” Mr. Biden said as he wrapped up his final answer, to a question about whether he supports the Endangered Species Act. (He does, he said. “Oh, I love you,” the questioner replied.) “There’s a lot more to say, but I’ve probably said too much to you,” Mr. Biden added.