One of them was Howard Dean, former governor of Vermont and Democratic National Committee chair.
"Notice Trump sniffing all the time," Dean tweeted on Monday. "Coke user?"
"That is actually a signature of people who use cocaine," Dean said of Trump's sniffling. "I'm not actually suggesting that Trump does."
Anchor Kate Snow then responded, "Well, you are suggesting it, actually, in a tweet."
"No, I'm suggesting we think about it," Dean replied. "He sniffs during the presentation, which is something that users do. He also has grandiosity, which is something that accompanies that problem. He has delusions — I'm not talking about being crazy, but for example when he told everybody it was very smart not to pay taxes then denied he said it after he said in front of 100 million people."
"He has trouble with pressured speech," Dean continued, citing Trump's repeated interruptions of Clinton during the debate.
"Look, do I think at 70 years old he has a cocaine habit? Probably not. But it'd be interesting to ask him to see if he ever had a problem with that."
"I think it's unlikely you could mount a presidential campaign at 70 years old with a cocaine habit, but it's pretty striking."
Dean said he would not delete the tweet or apologize for it.
A Trump spokesperson did not immediately respond to a request for comment.