Former President Donald Trump mocked Gov. Joe Bide's gaffe during a solo press conference Thursday night.

Trump appeared on Truth Social in the middle of a roughly hour-long press conference that followed growing calls within Biden's party for him to drop out. Trump began by criticizing Biden's “big boy” press conferences, as the Biden campaign called them last week. (RELATED: 'Time is ticking': Historian says Biden withdrawal is becoming 'less likely')

“Bad Boy Joe started his 'Big Boy' press conference with 'I wouldn't have picked VP Trump as my VP but I don't think she's qualified to be President.' Well done, Joe!” Trump posted.

Trump also posted two more videos in which Biden was seen stammering and struggling to finish his remarks.

“Vicky Joe has Trump Derangement Syndrome!” Trump further wrote.

Biden faced strong backlash after a poor performance in last month's debate with Trump, in which he struggled to finish his own sentences and froze up mid-sentence. After the debate, Democratic pundits immediately began questioning Biden's mental health and his ability to serve a full second term.

As a growing number of Democrats call for Biden to step down, Vermont Sen. Peter Welch on Wednesday became the first senator to publicly call for Biden to step down. Additionally, Democratic National Committee (DNC) Commissioner James Zogby wrote to party leaders in early July outlining plans for the party to potentially undertake a “managed process” to draft a new candidate.

Post-debate polls not only showed some Democrats were skeptical of Biden, but a CBS/YouGov poll found that 72% of Americans no longer believe Biden is in the mental and cognitive health necessary to hold the presidency. National polls also show Trump gaining support among voters. A new Economist/YouGov poll found: vote The survey, conducted July 7-9, showed Trump holding a three-point lead with 43% support, Biden on 40%, and other independent and Green Party candidates on a combined 7%.