"Kamala is labeling more than half of the country 'enemy combatants,' and she's calling them all 'fascists' and 'Nazis.' But she is a fascist, OK? She is a fascist," he said addressing his supporters at a rally in Atlanta.
Earlier, US media, citing emails from the political action committee Future Forward in support of Harris, warned that accusations of fascism against Trump were not convincing.
Earlier, Harris answered affirmatively on CNN when asked by the host whether she considered Trump a fascist.
The US presidential election will take place on November 5.