I like Vice President mike pence much better. He's solid as a rock," Mr Trump said. "He's been a great vice president, and I will take him over Kamala and the .... horrible way she treated Justice Kavanaugh.
"I thought she was the meanest, most disrespectful of anyone in the US Senate," the president claimed.
He also, like his campaign did in a statement, tried to describe Ms Harris as too liberal for most Americans, even amid questions about whether the progressive wing of the Democratic Party is fired up about her selection.
"She's known as being about the most liberal person in the United States Senate," Mr Trump said without citing any academic or think tank studies.
But a 2017 Pew Research Center study backs up the charge, grouping Ms Harris, based on her voting record in the "very liberal" portion of her party.