Former Vice President Joe Biden pushed back on former White House press secretary Sarah Sanders after she mocked him on social media for stuttering during the presidential debate.

Biden imitated a child stuttering while he was talking about the people he meets while campaigning during Thursday night's debate.

"My wife and I have a call list of somewhere between 20 and 100 people that we call at least every week or every month to tell them, 'I’m here.' I give them my private phone number. They keep in touch with me. The little kid who says, 'I-I-I-I-I-I-I can’t talk, what do I do?' I have scores of these young women and men who I keep in contact with," Biden said. "And the reason I would give everyone here a gift is because they want to do something like I do, making their lives better, because there’s a lot of people who are hurting very, very, very badly."

"I’ve worked my whole life to overcome a stutter. And it’s my great honor to mentor kids who have experienced the same. It’s called empathy. Look it up," the former vice president tweeted in response to Sanders, who posted, "I I I I I I I I I I I I I I I hhhave absolutely no idea what Biden is talking about. #DemDebate."

After the former White House spokeswoman faced condemnation on social media, she tweeted again, explaining that, "To be clear was not trying to make fun of anyone with a speech impediment. Simply pointing out I can’t follow much of anything Biden is talking about."

She later deleted the initial tweet and issued an apology saying, "I actually didn’t know that about you and that is commendable. I apologize and should have made my point respectfully."

On the campaign trail, Biden often refers to his childhood stuttering, and some have speculated he still suffers from the affliction.

"I used to stutter badly when I was a kid. So, I learned to fight. Not a joke," Biden said during a campaign stop in Decorah, Iowa. "When you're made fun of for something you can't control, you realize everybody has something about them they can't fully control ... their height, the color of their skin."