Fauci told host Chris Hayes that Paul was using their interaction to raise political contributions.

"[W]hat you saw at the hearing today was pure ad hominem," Fauci said. "And I called him out because that's exactly what he's doing. He's raising money: Vote here, paid for by Rand Paul. Fire Fauci. He's killing you. He's murdering people. He's doing this. And, by the way, donate here. Click this box."

"I mean, if that isn't absolutely proof of what's going on here, I mean, you can't miss that one, Chris," he added.