"She had about 2%, spent a lot of money ... I was surprised they chose her," Trump said at a press conference. His words are quoted by RIA Novosti.
According to the president, Harris "was very disrespectful to Joe Biden."
"She said terrible things about Sleepy Joe, and it's hard to imagine that he chose her," said Trump.
Earlier, the Democratic presidential candidate Joe Biden chose Harris as the candidate for the vice-president of the United States.
She, in turn, promised to do "whatever it takes" to help the politician become president.