Donald Trump has questioned the racial identity of Kamala Harris during a heated exchange on Wednesday,
The pair were speaking at a convention for the National Association of Black Journalists in Chicago, Illinois.
"I didn't know she was black until a number of years ago when she happened to turn black and now she wants to be known as black," said Mr Trump.
"So I don't know - Is she Indian? Or is she black?"
Ms Harris was quick to criticise Mr Trump's remarks, accusing him of "divisiveness and disrespect".
She added that the American people "deserve better", continuing to say: "We deserve a leader who understands that our differences do not divide us - they are an essential source of our strength."
Mr Trump, who was speaking to moderator Rachel Scott when he made the remarks, said he "respects either one", in reference to Ms Harris' identity.
He added: "But she obviously doesn't because she was Indian all the way and then all of a sudden she made a turn and she became a black person."
Karine Jean-Pierre, the White House press secretary, described what Mr Trump said as "repulsive" and "insulting".