WATCH | 'This clown' and 'Nothing smart about you': Un-presidential insults fly in first Trump-Biden debate

Interrupted repeatedly by US president Donald Trump in their presidential debate on Tuesday, an exasperated Joe Biden resorted to insults and name-calling against an opponent who built his political career by coining belittling nicknames for his rivals.

“You're the worst president America has ever had,” Biden, the Democratic presidential nominee, said during a back-and-forth on taxes.

The insults featured heavily during a chaotic encounter in which Trump often talked over Biden and moderator Chris Wallace.