Former vice president and presumptive Democratic presidential nominee Joe Biden has been open about his lifelong struggle to overcome his stutter and has devoted time to mentoring children with similar issues. As The Washington Post reported last year, it is a “central part of his political story.”

On Monday night, as Sean Hannity’s guests chortled, the Fox News host mockingly affected a stutter to ridicule the presidential hopeful.

For months now, President Donald Trump and his conservative media allies have attempted to frame Biden as mentally unfit for office, accusing him of being senile and suffering from cognitive decline. Hannity, a Trump confidant who is sometimes referred to as the White House shadow chief of staff, has led the charge in pushing this narrative.

Hours after Trump claimed the “1917” influenza pandemic ended World War II, Hannity hosted former White House physician Dr. Ronny Jackson and Trump campaign adviser Mercedes Schlapp to mock Biden’s latest interview gaffes.

After the panel agreed that Biden wasn’t “mentally fit” for office and couldn’t pass the same cognitive test that Trump took, Hannity aired a clip of Biden recently scolding a Black anchor for asking if he’s taken a cognitive exam.

“That’s like saying to you, before you got on this program, you take a test where you taking cocaine or not. What do you think? Huh? Are you a junkie?” Biden said at the time, sparking criticism and derision.

Elsewhere in the clip, Biden stumbled over the word “fitness,” briefly stuttering as he repeated the word a couple of times.

Paraphrasing Biden’s remarks, Hannity turned to Schlapp and began impersonating the ex-veep while exaggeratedly stammering when he tried to say “fitness.”

“And I’d put my physical and mental fuh,fuh—what’s that word again? Oh, oh, ohh! Fuh, fuh, fuh, fuh, fitness! Fitness!” Hannity exclaimed as Jackson and Schlapp laughed.

Last December, during a Democratic primary debate, former White House press secretary and current Fox News contributor Sarah Huckabee Sanders mockingly tweeted about Biden’s stutter. She eventually apologized.

At one point in that debate, Biden spoke about the stuttering children he’s mentored in the past, mimicking a stutter while recounting how a young kid told him “I can’t talk.” Sanders, meanwhile, tweeted moments later: “I I I I I I I I I I I I I I I hhhave absolutely no idea what Biden is talking about.”

She soon deleted the tweet after receiving swift backlash over it, despite initially insisting she wasn’t attempting to make fun of Biden’s stutter.